diff --git a/db/migrate/20120311163914_create_forum_threads.rb b/db/migrate/20120311163914_create_forum_threads.rb
index 28679158194..bf379f7367c 100644
--- a/db/migrate/20120311163914_create_forum_threads.rb
+++ b/db/migrate/20120311163914_create_forum_threads.rb
@@ -5,7 +5,7 @@ class CreateForumThreads < ActiveRecord::Migration
       t.string :title, null: false
       t.integer :last_post_id
       t.datetime :last_posted_at
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120311164326_create_posts.rb b/db/migrate/20120311164326_create_posts.rb
index 41108b2bd39..5408bb79acf 100644
--- a/db/migrate/20120311164326_create_posts.rb
+++ b/db/migrate/20120311164326_create_posts.rb
@@ -6,7 +6,7 @@ class CreatePosts < ActiveRecord::Migration
       t.integer :post_number, null: false
       t.text :content, null: false
       t.text :formatted_content, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :posts, [:forum_thread_id, :created_at]
diff --git a/db/migrate/20120311170118_create_users.rb b/db/migrate/20120311170118_create_users.rb
index d8dcdf1b9f2..e2131e679f7 100644
--- a/db/migrate/20120311170118_create_users.rb
+++ b/db/migrate/20120311170118_create_users.rb
@@ -3,7 +3,7 @@ class CreateUsers < ActiveRecord::Migration
     create_table :users do |t|
       t.string :username, limit: 20, null: false
       t.string :avatar_url, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120311201341_create_forums.rb b/db/migrate/20120311201341_create_forums.rb
index 748c6f6eeff..a1a76480c32 100644
--- a/db/migrate/20120311201341_create_forums.rb
+++ b/db/migrate/20120311201341_create_forums.rb
@@ -3,7 +3,7 @@ class CreateForums < ActiveRecord::Migration
     create_table :forums do |t|
       t.integer :site_id, null: false
       t.string :title, limit: 100, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120311210245_create_sites.rb b/db/migrate/20120311210245_create_sites.rb
index d281148641c..b16d2b6ddf3 100644
--- a/db/migrate/20120311210245_create_sites.rb
+++ b/db/migrate/20120311210245_create_sites.rb
@@ -2,7 +2,7 @@ class CreateSites < ActiveRecord::Migration
   def change
     create_table :sites  do |t|
       t.string :title, limit: 100, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120427154330_create_vestal_versions.rb b/db/migrate/20120427154330_create_vestal_versions.rb
index f9121132915..4249254f930 100644
--- a/db/migrate/20120427154330_create_vestal_versions.rb
+++ b/db/migrate/20120427154330_create_vestal_versions.rb
@@ -9,7 +9,7 @@ class CreateVestalVersions < ActiveRecord::Migration
       t.integer :reverted_from
       t.string  :tag
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     change_table :versions do |t|
diff --git a/db/migrate/20120507144132_create_expressions.rb b/db/migrate/20120507144132_create_expressions.rb
index 2cf61712fe4..7dde3ad29d2 100644
--- a/db/migrate/20120507144132_create_expressions.rb
+++ b/db/migrate/20120507144132_create_expressions.rb
@@ -5,7 +5,7 @@ class CreateExpressions < ActiveRecord::Migration
       t.string :parent_type, null: false, limit: 50
       t.integer :expression_type_id, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :expressions, [:parent_id, :parent_type, :expression_type_id, :user_id], unique: true, name: "expressions_pk"
diff --git a/db/migrate/20120507144222_create_expression_types.rb b/db/migrate/20120507144222_create_expression_types.rb
index 37cd4d0a360..68efefb4b8c 100644
--- a/db/migrate/20120507144222_create_expression_types.rb
+++ b/db/migrate/20120507144222_create_expression_types.rb
@@ -4,7 +4,7 @@ class CreateExpressionTypes < ActiveRecord::Migration
       t.integer :site_id, null: false
       t.string :name, null: false, limit: 50
       t.string :long_form, null: false, limit: 100
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :expression_types, [:site_id, :name], unique: true
diff --git a/db/migrate/20120519182212_create_last_read_posts.rb b/db/migrate/20120519182212_create_last_read_posts.rb
index c2d1e7b3821..6bbb21fc2e3 100644
--- a/db/migrate/20120519182212_create_last_read_posts.rb
+++ b/db/migrate/20120519182212_create_last_read_posts.rb
@@ -4,7 +4,7 @@ class CreateLastReadPosts < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :forum_thread_id, null: false
       t.integer :post_number, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :last_read_posts, [:user_id, :forum_thread_id], unique: true
diff --git a/db/migrate/20120529175956_create_uploads.rb b/db/migrate/20120529175956_create_uploads.rb
index b0eb7984473..2a5ddc36a0e 100644
--- a/db/migrate/20120529175956_create_uploads.rb
+++ b/db/migrate/20120529175956_create_uploads.rb
@@ -8,7 +8,7 @@ class CreateUploads < ActiveRecord::Migration
       t.integer :width, null: true
       t.integer :height, null: true
       t.string  :url, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :uploads, :forum_thread_id
diff --git a/db/migrate/20120529202707_create_stars.rb b/db/migrate/20120529202707_create_stars.rb
index 91c609ac315..8c5133c326e 100644
--- a/db/migrate/20120529202707_create_stars.rb
+++ b/db/migrate/20120529202707_create_stars.rb
@@ -4,7 +4,7 @@ class CreateStars < ActiveRecord::Migration
       t.integer  :parent_id, null: false
       t.string   :parent_type, limit: 50, null: false
       t.integer  :user_id, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :stars, [:parent_id, :parent_type, :user_id]
diff --git a/db/migrate/20120530150726_create_forum_thread_user.rb b/db/migrate/20120530150726_create_forum_thread_user.rb
index 98ecd85a84c..e74e053641d 100644
--- a/db/migrate/20120530150726_create_forum_thread_user.rb
+++ b/db/migrate/20120530150726_create_forum_thread_user.rb
@@ -6,7 +6,7 @@ class CreateForumThreadUser < ActiveRecord::Migration
       t.boolean  :starred, null: false, default: false
       t.boolean  :posted, null: false, default: false
       t.integer  :last_read_post_number, null: false, default: 1
-      t.timestamps
+      t.timestamps null: false
     end
 
     execute "DELETE FROM read_posts"
@@ -24,7 +24,7 @@ class CreateForumThreadUser < ActiveRecord::Migration
       t.integer  :parent_id, null: false
       t.string   :parent_type, limit: 50, null: false
       t.integer  :user_id, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :stars, [:parent_id, :parent_type, :user_id]
@@ -33,7 +33,7 @@ class CreateForumThreadUser < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :forum_thread_id, null: false
       t.integer :post_number, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :last_read_posts, [:user_id, :forum_thread_id], unique: true
diff --git a/db/migrate/20120530212912_create_forum_thread_links.rb b/db/migrate/20120530212912_create_forum_thread_links.rb
index 91cb347a82e..7e137206fa2 100644
--- a/db/migrate/20120530212912_create_forum_thread_links.rb
+++ b/db/migrate/20120530212912_create_forum_thread_links.rb
@@ -8,7 +8,7 @@ class CreateForumThreadLinks < ActiveRecord::Migration
       t.string  :domain, limit: 100, null: false
       t.boolean :internal, null: false, default: false
       t.integer :link_forum_thread_id, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :forum_thread_links, :forum_thread_id
diff --git a/db/migrate/20120615180517_create_bookmarks.rb b/db/migrate/20120615180517_create_bookmarks.rb
index 5e129e89500..a1c9c28d007 100644
--- a/db/migrate/20120615180517_create_bookmarks.rb
+++ b/db/migrate/20120615180517_create_bookmarks.rb
@@ -3,7 +3,7 @@ class CreateBookmarks < ActiveRecord::Migration
     create_table :bookmarks do |t|
       t.integer :user_id
       t.integer :post_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :bookmarks, [:user_id, :post_id], unique: true
diff --git a/db/migrate/20120619172714_add_post_number_to_bookmarks.rb b/db/migrate/20120619172714_add_post_number_to_bookmarks.rb
index 6cbf8151ba4..3d997ed2bc3 100644
--- a/db/migrate/20120619172714_add_post_number_to_bookmarks.rb
+++ b/db/migrate/20120619172714_add_post_number_to_bookmarks.rb
@@ -6,7 +6,7 @@ class AddPostNumberToBookmarks < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :forum_thread_id, null: false
       t.integer :post_number, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :bookmarks, [:user_id, :forum_thread_id, :post_number], unique: true
diff --git a/db/migrate/20120622200242_create_notifications.rb b/db/migrate/20120622200242_create_notifications.rb
index f97550bbf4f..51813b931ac 100644
--- a/db/migrate/20120622200242_create_notifications.rb
+++ b/db/migrate/20120622200242_create_notifications.rb
@@ -5,7 +5,7 @@ class CreateNotifications < ActiveRecord::Migration
       t.references :user, null: false
       t.string :data, null: false
       t.boolean :read, default: false, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :notifications, [:user_id, :created_at]
diff --git a/db/migrate/20120629182637_create_incoming_links.rb b/db/migrate/20120629182637_create_incoming_links.rb
index d5215c1ecec..319ede0bff5 100644
--- a/db/migrate/20120629182637_create_incoming_links.rb
+++ b/db/migrate/20120629182637_create_incoming_links.rb
@@ -7,7 +7,7 @@ class CreateIncomingLinks < ActiveRecord::Migration
       t.string :domain, limit: 100, null: false
       t.integer :forum_thread_id, null: true
       t.integer :post_number, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :incoming_links, [:site_id, :forum_thread_id, :post_number], name: 'incoming_index'
diff --git a/db/migrate/20120702211427_create_replies.rb b/db/migrate/20120702211427_create_replies.rb
index cf8e80e3d0f..bc65dd9f9df 100644
--- a/db/migrate/20120702211427_create_replies.rb
+++ b/db/migrate/20120702211427_create_replies.rb
@@ -3,7 +3,7 @@ class CreateReplies < ActiveRecord::Migration
     create_table :post_replies, id: false do |t|
       t.references :post
       t.integer :reply_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :post_replies, [:post_id, :reply_id], unique: true
diff --git a/db/migrate/20120712150500_create_categories.rb b/db/migrate/20120712150500_create_categories.rb
index 3cd4ccdd796..6479e0596bd 100644
--- a/db/migrate/20120712150500_create_categories.rb
+++ b/db/migrate/20120712150500_create_categories.rb
@@ -9,7 +9,7 @@ class CreateCategories < ActiveRecord::Migration
       t.integer :top1_user_id, null: true
       t.integer :top2_user_id, null: true
       t.integer :forum_thread_count, null: false, default: 0
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :categories, :name, unique: true
diff --git a/db/migrate/20120713201324_create_category_featured_threads.rb b/db/migrate/20120713201324_create_category_featured_threads.rb
index 170ff49b81e..46752f44abe 100644
--- a/db/migrate/20120713201324_create_category_featured_threads.rb
+++ b/db/migrate/20120713201324_create_category_featured_threads.rb
@@ -3,7 +3,7 @@ class CreateCategoryFeaturedThreads < ActiveRecord::Migration
     create_table :category_featured_threads, id: false do |t|
       t.references :category, null: false
       t.references :forum_thread, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :category_featured_threads, [:category_id, :forum_thread_id], unique: true, name: 'cat_featured_threads'
diff --git a/db/migrate/20120716020835_create_site_settings.rb b/db/migrate/20120716020835_create_site_settings.rb
index f519c89b5e5..a5cdd44459e 100644
--- a/db/migrate/20120716020835_create_site_settings.rb
+++ b/db/migrate/20120716020835_create_site_settings.rb
@@ -6,7 +6,7 @@ class CreateSiteSettings < ActiveRecord::Migration
       t.integer :data_type, null: false
       t.text :value
 
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120718044955_create_user_open_ids.rb b/db/migrate/20120718044955_create_user_open_ids.rb
index 62cb7ff36c4..95b87c5aae1 100644
--- a/db/migrate/20120718044955_create_user_open_ids.rb
+++ b/db/migrate/20120718044955_create_user_open_ids.rb
@@ -4,7 +4,7 @@ class CreateUserOpenIds < ActiveRecord::Migration
       t.integer :user_id
       t.string :email
       t.string :url
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_open_ids, [:url]
diff --git a/db/migrate/20120807223020_create_actions.rb b/db/migrate/20120807223020_create_actions.rb
index ace59397854..a720e4e8b78 100644
--- a/db/migrate/20120807223020_create_actions.rb
+++ b/db/migrate/20120807223020_create_actions.rb
@@ -15,7 +15,7 @@ class CreateActions < ActiveRecord::Migration
       t.integer :target_user_id
       t.integer :acting_user_id
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :actions, [:user_id, :action_type]
diff --git a/db/migrate/20120809174649_create_post_actions.rb b/db/migrate/20120809174649_create_post_actions.rb
index 7a8e5d9f440..7a15a29fcff 100644
--- a/db/migrate/20120809174649_create_post_actions.rb
+++ b/db/migrate/20120809174649_create_post_actions.rb
@@ -5,7 +5,7 @@ class CreatePostActions < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :post_action_type_id, null: false
       t.datetime :deleted_at
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :post_actions, ["post_id"]
diff --git a/db/migrate/20120809175110_create_post_action_types.rb b/db/migrate/20120809175110_create_post_action_types.rb
index c738031ca91..410547b6de8 100644
--- a/db/migrate/20120809175110_create_post_action_types.rb
+++ b/db/migrate/20120809175110_create_post_action_types.rb
@@ -8,7 +8,7 @@ class CreatePostActionTypes < ActiveRecord::Migration
       t.text :description
       t.string :icon, limit: 20
 
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20120813201426_create_forum_thread_link_clicks.rb b/db/migrate/20120813201426_create_forum_thread_link_clicks.rb
index f87202cfb50..c216f836ace 100644
--- a/db/migrate/20120813201426_create_forum_thread_link_clicks.rb
+++ b/db/migrate/20120813201426_create_forum_thread_link_clicks.rb
@@ -4,7 +4,7 @@ class CreateForumThreadLinkClicks < ActiveRecord::Migration
       t.references :forum_thread_link, null: false
       t.references :user, null: true
       t.integer :ip, null: false, limit: 8
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_column :forum_thread_links, :clicks, :integer, default: 0, null: false
diff --git a/db/migrate/20120824171908_create_category_featured_users.rb b/db/migrate/20120824171908_create_category_featured_users.rb
index 27c3fadd5bc..db72c45b5cd 100644
--- a/db/migrate/20120824171908_create_category_featured_users.rb
+++ b/db/migrate/20120824171908_create_category_featured_users.rb
@@ -3,7 +3,7 @@ class CreateCategoryFeaturedUsers < ActiveRecord::Migration
     create_table :category_featured_users do |t|
       t.references :category
       t.references :user
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :category_featured_users, [:category_id, :user_id], unique: true
diff --git a/db/migrate/20120828204209_create_onebox_renders.rb b/db/migrate/20120828204209_create_onebox_renders.rb
index 85b60d7654d..c28657b7ca5 100644
--- a/db/migrate/20120828204209_create_onebox_renders.rb
+++ b/db/migrate/20120828204209_create_onebox_renders.rb
@@ -4,7 +4,7 @@ class CreateOneboxRenders < ActiveRecord::Migration
       t.string :url, null: false
       t.text :cooked, null: false
       t.datetime :expires_at, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :onebox_renders, :url, unique: true
diff --git a/db/migrate/20120828204624_create_post_onebox_renders.rb b/db/migrate/20120828204624_create_post_onebox_renders.rb
index 19c70e14295..4a991a14f9c 100644
--- a/db/migrate/20120828204624_create_post_onebox_renders.rb
+++ b/db/migrate/20120828204624_create_post_onebox_renders.rb
@@ -3,7 +3,7 @@ class CreatePostOneboxRenders < ActiveRecord::Migration
     create_table :post_onebox_renders, id: false do |t|
       t.references :post, null: false
       t.references :onebox_render, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :post_onebox_renders, [:post_id, :onebox_render_id], unique: true
   end
diff --git a/db/migrate/20120921055428_add_twitter_user_info.rb b/db/migrate/20120921055428_add_twitter_user_info.rb
index 7aa0f81f0c9..8830ef0175d 100644
--- a/db/migrate/20120921055428_add_twitter_user_info.rb
+++ b/db/migrate/20120921055428_add_twitter_user_info.rb
@@ -4,7 +4,7 @@ class AddTwitterUserInfo < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :screen_name, null: false
       t.integer :twitter_user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :twitter_user_infos, [:twitter_user_id], unique: true
diff --git a/db/migrate/20120921155050_create_archetypes.rb b/db/migrate/20120921155050_create_archetypes.rb
index 59e716913c0..59bca0e28e9 100644
--- a/db/migrate/20120921155050_create_archetypes.rb
+++ b/db/migrate/20120921155050_create_archetypes.rb
@@ -2,7 +2,7 @@ class CreateArchetypes < ActiveRecord::Migration
   def up
     create_table :archetypes do |t|
       t.string :name_key, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :archetypes, :name_key, unique: true
 
diff --git a/db/migrate/20120921163606_create_archetype_options.rb b/db/migrate/20120921163606_create_archetype_options.rb
index acac37d8978..9ddc71fc071 100644
--- a/db/migrate/20120921163606_create_archetype_options.rb
+++ b/db/migrate/20120921163606_create_archetype_options.rb
@@ -4,7 +4,7 @@ class CreateArchetypeOptions < ActiveRecord::Migration
       t.references :archetype, null: false
       t.string :key, null: false
       t.integer :option_type, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :archetype_options, :archetype_id
diff --git a/db/migrate/20121011155904_create_email_logs.rb b/db/migrate/20121011155904_create_email_logs.rb
index abfea55e767..a4b0c49e4eb 100644
--- a/db/migrate/20121011155904_create_email_logs.rb
+++ b/db/migrate/20121011155904_create_email_logs.rb
@@ -4,7 +4,7 @@ class CreateEmailLogs < ActiveRecord::Migration
       t.string :to_address, null: false
       t.string :email_type, null: false
       t.integer :user_id, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :email_logs, :created_at, order: { created_at: :desc }
diff --git a/db/migrate/20121018133039_create_topic_allowed_users.rb b/db/migrate/20121018133039_create_topic_allowed_users.rb
index 04a832f60fe..b3d4324fcb7 100644
--- a/db/migrate/20121018133039_create_topic_allowed_users.rb
+++ b/db/migrate/20121018133039_create_topic_allowed_users.rb
@@ -3,7 +3,7 @@ class CreateTopicAllowedUsers < ActiveRecord::Migration
     create_table :topic_allowed_users do |t|
       t.integer :user_id, null: false
       t.integer :topic_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :topic_allowed_users, [:topic_id, :user_id], unique: true
diff --git a/db/migrate/20121109164630_create_trust_levels.rb b/db/migrate/20121109164630_create_trust_levels.rb
index 16a1e70c161..6c3983e8925 100644
--- a/db/migrate/20121109164630_create_trust_levels.rb
+++ b/db/migrate/20121109164630_create_trust_levels.rb
@@ -2,7 +2,7 @@ class CreateTrustLevels < ActiveRecord::Migration
   def change
     create_table :trust_levels do |t|
       t.string :name_key, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_column :users, :trust_level_id, :integer, default: 1, null: false
diff --git a/db/migrate/20121113200845_create_facebook_user_infos.rb b/db/migrate/20121113200845_create_facebook_user_infos.rb
index aa9c29099d3..1ef46b480b6 100644
--- a/db/migrate/20121113200845_create_facebook_user_infos.rb
+++ b/db/migrate/20121113200845_create_facebook_user_infos.rb
@@ -11,7 +11,7 @@ class CreateFacebookUserInfos < ActiveRecord::Migration
       t.string :name
       t.string :link
 
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :facebook_user_infos, :user_id, unique: true
     add_index :facebook_user_infos, :facebook_user_id, unique: true
diff --git a/db/migrate/20121121202035_create_invites.rb b/db/migrate/20121121202035_create_invites.rb
index 727f4561649..71ef5c2f1a6 100644
--- a/db/migrate/20121121202035_create_invites.rb
+++ b/db/migrate/20121121202035_create_invites.rb
@@ -6,7 +6,7 @@ class CreateInvites < ActiveRecord::Migration
       t.integer :invited_by_id, null: false
       t.integer :user_id, null: true
       t.timestamp :redeemed_at, null: true
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :invites, :invite_key, unique: true
diff --git a/db/migrate/20121121205215_create_topic_invites.rb b/db/migrate/20121121205215_create_topic_invites.rb
index 75a58b2ee97..45fb2d59510 100644
--- a/db/migrate/20121121205215_create_topic_invites.rb
+++ b/db/migrate/20121121205215_create_topic_invites.rb
@@ -3,7 +3,7 @@ class CreateTopicInvites < ActiveRecord::Migration
     create_table :topic_invites do |t|
       t.references :topic, null: false
       t.references :invite, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :topic_invites, [:topic_id, :invite_id], unique: true
diff --git a/db/migrate/20121129160035_create_email_tokens.rb b/db/migrate/20121129160035_create_email_tokens.rb
index 6dcfd64c322..c4ade0f0cc2 100644
--- a/db/migrate/20121129160035_create_email_tokens.rb
+++ b/db/migrate/20121129160035_create_email_tokens.rb
@@ -6,7 +6,7 @@ class CreateEmailTokens < ActiveRecord::Migration
       t.string :token, null: false
       t.boolean :confirmed, null: false, default: false
       t.boolean :expired, null: false, default: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :email_tokens, :token, unique: true
   end
diff --git a/db/migrate/20121130010400_create_drafts.rb b/db/migrate/20121130010400_create_drafts.rb
index 085e01ae542..dba5708226a 100644
--- a/db/migrate/20121130010400_create_drafts.rb
+++ b/db/migrate/20121130010400_create_drafts.rb
@@ -4,7 +4,7 @@ class CreateDrafts < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :draft_key, null: false
       t.text :data, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :drafts, [:user_id, :draft_key]
   end
diff --git a/db/migrate/20121211233131_create_site_customizations.rb b/db/migrate/20121211233131_create_site_customizations.rb
index 0e19a3f3690..dd39279f4f7 100644
--- a/db/migrate/20121211233131_create_site_customizations.rb
+++ b/db/migrate/20121211233131_create_site_customizations.rb
@@ -8,7 +8,7 @@ class CreateSiteCustomizations < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.boolean :enabled, null: false
       t.string :key, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :site_customizations, [:key]
diff --git a/db/migrate/20130226015336_add_github_user_info.rb b/db/migrate/20130226015336_add_github_user_info.rb
index 431fb29d983..6d575d1c034 100644
--- a/db/migrate/20130226015336_add_github_user_info.rb
+++ b/db/migrate/20130226015336_add_github_user_info.rb
@@ -4,7 +4,7 @@ class AddGithubUserInfo < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :screen_name, null: false
       t.integer :github_user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :github_user_infos, [:github_user_id], unique: true
diff --git a/db/migrate/20130404143437_create_site_contents.rb b/db/migrate/20130404143437_create_site_contents.rb
index c4554c91167..f4241a6a464 100644
--- a/db/migrate/20130404143437_create_site_contents.rb
+++ b/db/migrate/20130404143437_create_site_contents.rb
@@ -3,7 +3,7 @@ class CreateSiteContents < ActiveRecord::Migration
     create_table :site_contents, force: true, id: false do |t|
       t.string :content_type, null: false
       t.text :content, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :site_contents, :content_type, unique: true
   end
diff --git a/db/migrate/20130411205132_create_admin_logs.rb b/db/migrate/20130411205132_create_admin_logs.rb
index 197bea30cd6..f79b27f06a3 100644
--- a/db/migrate/20130411205132_create_admin_logs.rb
+++ b/db/migrate/20130411205132_create_admin_logs.rb
@@ -5,7 +5,7 @@ class CreateAdminLogs < ActiveRecord::Migration
       t.integer :admin_id,        null: false
       t.integer :target_user_id
       t.text    :details
-      t.timestamps
+      t.timestamps null: false
     end
   end
 
diff --git a/db/migrate/20130416004607_create_groups.rb b/db/migrate/20130416004607_create_groups.rb
index f684f3fc3c4..30969acad14 100644
--- a/db/migrate/20130416004607_create_groups.rb
+++ b/db/migrate/20130416004607_create_groups.rb
@@ -2,7 +2,7 @@ class CreateGroups < ActiveRecord::Migration
   def change
     create_table :groups, force: true do |t|
       t.string :name, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20130416004933_group_users.rb b/db/migrate/20130416004933_group_users.rb
index 024d6caaa4d..3dfa140dc49 100644
--- a/db/migrate/20130416004933_group_users.rb
+++ b/db/migrate/20130416004933_group_users.rb
@@ -3,7 +3,7 @@ class GroupUsers < ActiveRecord::Migration
     create_table :group_users, force: true do |t|
       t.integer :group_id, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :group_users, [:group_id, :user_id], unique: true
diff --git a/db/migrate/20130429000101_add_security_to_categories.rb b/db/migrate/20130429000101_add_security_to_categories.rb
index 04f0314112b..5881bf07ad8 100644
--- a/db/migrate/20130429000101_add_security_to_categories.rb
+++ b/db/migrate/20130429000101_add_security_to_categories.rb
@@ -5,7 +5,7 @@ class AddSecurityToCategories < ActiveRecord::Migration
     create_table :category_groups, force: true do |t|
       t.integer :category_id, null: false
       t.integer :group_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20130521210140_create_cas_user_infos.rb b/db/migrate/20130521210140_create_cas_user_infos.rb
index befadc56aa6..227429e9e6d 100644
--- a/db/migrate/20130521210140_create_cas_user_infos.rb
+++ b/db/migrate/20130521210140_create_cas_user_infos.rb
@@ -11,7 +11,7 @@ class CreateCasUserInfos < ActiveRecord::Migration
       t.string :name
       t.string :link
 
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :cas_user_infos, :user_id, unique: true
     add_index :cas_user_infos, :cas_user_id, unique: true
diff --git a/db/migrate/20130724201552_create_blocked_emails.rb b/db/migrate/20130724201552_create_blocked_emails.rb
index 2c669e3ee1e..557c1363899 100644
--- a/db/migrate/20130724201552_create_blocked_emails.rb
+++ b/db/migrate/20130724201552_create_blocked_emails.rb
@@ -5,7 +5,7 @@ class CreateBlockedEmails < ActiveRecord::Migration
       t.integer :action_type, null: false
       t.integer :match_count, null: false, default: 0
       t.datetime :last_match_at
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :blocked_emails, :email, unique: true
   end
diff --git a/db/migrate/20130813204212_create_screened_urls.rb b/db/migrate/20130813204212_create_screened_urls.rb
index 5e613c748e9..d5e6e3ba892 100644
--- a/db/migrate/20130813204212_create_screened_urls.rb
+++ b/db/migrate/20130813204212_create_screened_urls.rb
@@ -6,7 +6,7 @@ class CreateScreenedUrls < ActiveRecord::Migration
       t.integer :action_type, null: false
       t.integer :match_count, null: false, default: 0
       t.datetime :last_match_at
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :screened_urls, :url, unique: true
     add_index :screened_urls, :last_match_at
diff --git a/db/migrate/20130816024250_create_oauth2_user_infos.rb b/db/migrate/20130816024250_create_oauth2_user_infos.rb
index d5a392fb61d..d70ab81cc91 100644
--- a/db/migrate/20130816024250_create_oauth2_user_infos.rb
+++ b/db/migrate/20130816024250_create_oauth2_user_infos.rb
@@ -6,7 +6,7 @@ class CreateOauth2UserInfos < ActiveRecord::Migration
       t.string :provider, null: false
       t.string :email
       t.string :name
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :oauth2_user_infos, [:uid, :provider], unique: true
diff --git a/db/migrate/20131015131652_create_post_details.rb b/db/migrate/20131015131652_create_post_details.rb
index 5a124432cf6..ab912848257 100644
--- a/db/migrate/20131015131652_create_post_details.rb
+++ b/db/migrate/20131015131652_create_post_details.rb
@@ -6,7 +6,7 @@ class CreatePostDetails < ActiveRecord::Migration
       t.string     :value, size: 512
       t.text       :extra
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :post_details, [:post_id, :key], unique: true
diff --git a/db/migrate/20131017205954_create_screened_ip_addresses.rb b/db/migrate/20131017205954_create_screened_ip_addresses.rb
index 63968f05fff..1c16e519065 100644
--- a/db/migrate/20131017205954_create_screened_ip_addresses.rb
+++ b/db/migrate/20131017205954_create_screened_ip_addresses.rb
@@ -5,7 +5,7 @@ class CreateScreenedIpAddresses < ActiveRecord::Migration
       t.integer :action_type, null: false
       t.integer :match_count, null: false, default: 0
       t.datetime :last_match_at
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :screened_ip_addresses, :ip_address, unique: true
     add_index :screened_ip_addresses, :last_match_at
diff --git a/db/migrate/20131022151218_create_api_keys.rb b/db/migrate/20131022151218_create_api_keys.rb
index a9f938b8387..4cd05991987 100644
--- a/db/migrate/20131022151218_create_api_keys.rb
+++ b/db/migrate/20131022151218_create_api_keys.rb
@@ -5,7 +5,7 @@ class CreateApiKeys < ActiveRecord::Migration
       t.string :key, limit: 64, null: false
       t.integer :user_id, null: true
       t.integer :created_by_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :api_keys, :key
diff --git a/db/migrate/20131209091702_create_post_revisions.rb b/db/migrate/20131209091702_create_post_revisions.rb
index 7d12d8cb88c..f9d613361ba 100644
--- a/db/migrate/20131209091702_create_post_revisions.rb
+++ b/db/migrate/20131209091702_create_post_revisions.rb
@@ -5,7 +5,7 @@ class CreatePostRevisions < ActiveRecord::Migration
       t.belongs_to :post
       t.text :modifications
       t.integer :number
-      t.timestamps
+      t.timestamps null: false
     end
 
     execute "INSERT INTO post_revisions (user_id, post_id, modifications, number, created_at, updated_at)
diff --git a/db/migrate/20131209091742_create_topic_revisions.rb b/db/migrate/20131209091742_create_topic_revisions.rb
index a6bddd046de..94d89bc6dde 100644
--- a/db/migrate/20131209091742_create_topic_revisions.rb
+++ b/db/migrate/20131209091742_create_topic_revisions.rb
@@ -5,7 +5,7 @@ class CreateTopicRevisions < ActiveRecord::Migration
       t.belongs_to :topic
       t.text :modifications
       t.integer :number
-      t.timestamps
+      t.timestamps null: false
     end
 
     execute "INSERT INTO topic_revisions (user_id, topic_id, modifications, number, created_at, updated_at)
diff --git a/db/migrate/20131217174004_create_topic_embeds.rb b/db/migrate/20131217174004_create_topic_embeds.rb
index d887ff890b4..81de1d93957 100644
--- a/db/migrate/20131217174004_create_topic_embeds.rb
+++ b/db/migrate/20131217174004_create_topic_embeds.rb
@@ -5,7 +5,7 @@ class CreateTopicEmbeds < ActiveRecord::Migration
       t.integer :post_id, null: false
       t.string :embed_url, null: false
       t.string :content_sha1, null: false, limit: 40
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :topic_embeds, :embed_url, unique: true
diff --git a/db/migrate/20140224232913_add_single_sign_on_records.rb b/db/migrate/20140224232913_add_single_sign_on_records.rb
index 8daa750a7f0..c0321c617cc 100644
--- a/db/migrate/20140224232913_add_single_sign_on_records.rb
+++ b/db/migrate/20140224232913_add_single_sign_on_records.rb
@@ -4,7 +4,7 @@ class AddSingleSignOnRecords < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :external_id, null: false, length: 255
       t.text :last_payload, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :single_sign_on_records, :external_id, unique: true
diff --git a/db/migrate/20140304200606_create_badge_types.rb b/db/migrate/20140304200606_create_badge_types.rb
index e580c3a1e95..1ddffbfe715 100644
--- a/db/migrate/20140304200606_create_badge_types.rb
+++ b/db/migrate/20140304200606_create_badge_types.rb
@@ -4,7 +4,7 @@ class CreateBadgeTypes < ActiveRecord::Migration
       t.string :name, null: false
       t.string :color_hexcode, null: false
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :badge_types, [:name], unique: true
diff --git a/db/migrate/20140304201403_create_badges.rb b/db/migrate/20140304201403_create_badges.rb
index 1fbc9b52af4..89550ea9d26 100644
--- a/db/migrate/20140304201403_create_badges.rb
+++ b/db/migrate/20140304201403_create_badges.rb
@@ -6,7 +6,7 @@ class CreateBadges < ActiveRecord::Migration
       t.integer :badge_type_id, index: true, null: false
       t.integer :grant_count, null: false, default: 0
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :badges, [:name], unique: true
diff --git a/db/migrate/20140416202746_create_color_schemes.rb b/db/migrate/20140416202746_create_color_schemes.rb
index e6491c0b967..99e6a346c74 100644
--- a/db/migrate/20140416202746_create_color_schemes.rb
+++ b/db/migrate/20140416202746_create_color_schemes.rb
@@ -7,7 +7,7 @@ class CreateColorSchemes < ActiveRecord::Migration
       t.integer :versioned_id
       t.integer :version,      null: false, default: 1
 
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20140416202801_create_color_scheme_colors.rb b/db/migrate/20140416202801_create_color_scheme_colors.rb
index bed6d5fac7c..735d1f382f8 100644
--- a/db/migrate/20140416202801_create_color_scheme_colors.rb
+++ b/db/migrate/20140416202801_create_color_scheme_colors.rb
@@ -6,7 +6,7 @@ class CreateColorSchemeColors < ActiveRecord::Migration
       t.integer :opacity,         null: false, default: 100
       t.integer :color_scheme_id, null: false
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :color_scheme_colors, [:color_scheme_id]
diff --git a/db/migrate/20140421235646_add_user_custom_fields.rb b/db/migrate/20140421235646_add_user_custom_fields.rb
index 59c36589467..c6873949f3e 100644
--- a/db/migrate/20140421235646_add_user_custom_fields.rb
+++ b/db/migrate/20140421235646_add_user_custom_fields.rb
@@ -4,7 +4,7 @@ class AddUserCustomFields < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :name, limit: 256, null: false
       t.text :value
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_custom_fields, [:user_id, :name]
diff --git a/db/migrate/20140425125742_add_custom_fields.rb b/db/migrate/20140425125742_add_custom_fields.rb
index 3b6c542fde4..51f5f7c55c3 100644
--- a/db/migrate/20140425125742_add_custom_fields.rb
+++ b/db/migrate/20140425125742_add_custom_fields.rb
@@ -4,21 +4,21 @@ class AddCustomFields < ActiveRecord::Migration
       t.integer :category_id, null: false
       t.string :name, limit: 256, null: false
       t.text :value
-      t.timestamps
+      t.timestamps null: false
     end
 
     create_table :group_custom_fields do |t|
       t.integer :group_id, null: false
       t.string :name, limit: 256, null: false
       t.text :value
-      t.timestamps
+      t.timestamps null: false
     end
 
     create_table :post_custom_fields do |t|
       t.integer :post_id, null: false
       t.string :name, limit: 256, null: false
       t.text :value
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :category_custom_fields, [:category_id, :name]
diff --git a/db/migrate/20140425135354_add_topic_custom_fields.rb b/db/migrate/20140425135354_add_topic_custom_fields.rb
index 4a059f8a628..8b0a8987d73 100644
--- a/db/migrate/20140425135354_add_topic_custom_fields.rb
+++ b/db/migrate/20140425135354_add_topic_custom_fields.rb
@@ -4,7 +4,7 @@ class AddTopicCustomFields < ActiveRecord::Migration
       t.integer :topic_id, null: false
       t.string :name, limit: 256, null: false
       t.text :value
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :topic_custom_fields, [:topic_id, :name]
diff --git a/db/migrate/20140508053815_add_invited_groups.rb b/db/migrate/20140508053815_add_invited_groups.rb
index 09a51ee1ac9..a29d74550bb 100644
--- a/db/migrate/20140508053815_add_invited_groups.rb
+++ b/db/migrate/20140508053815_add_invited_groups.rb
@@ -3,7 +3,7 @@ class AddInvitedGroups < ActiveRecord::Migration
     create_table :invited_groups do |t|
       t.integer :group_id
       t.integer :invite_id
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20140521192142_create_google_user_infos.rb b/db/migrate/20140521192142_create_google_user_infos.rb
index 28da7b547c6..a548447c2b7 100644
--- a/db/migrate/20140521192142_create_google_user_infos.rb
+++ b/db/migrate/20140521192142_create_google_user_infos.rb
@@ -12,7 +12,7 @@ class CreateGoogleUserInfos < ActiveRecord::Migration
       t.string :profile_link
       t.string :picture
 
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :google_user_infos, :user_id, unique: true
     add_index :google_user_infos, :google_user_id, unique: true
diff --git a/db/migrate/20140522003151_add_user_avatars.rb b/db/migrate/20140522003151_add_user_avatars.rb
index cb9a51348aa..025a233be1e 100644
--- a/db/migrate/20140522003151_add_user_avatars.rb
+++ b/db/migrate/20140522003151_add_user_avatars.rb
@@ -6,7 +6,7 @@ class AddUserAvatars < ActiveRecord::Migration
       t.integer :custom_upload_id
       t.integer :gravatar_upload_id
       t.datetime :last_gravatar_download_attempt
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_avatars, [:user_id]
diff --git a/db/migrate/20140715055242_add_quoted_posts.rb b/db/migrate/20140715055242_add_quoted_posts.rb
index 5f6c79cd3ec..6dd573e031e 100644
--- a/db/migrate/20140715055242_add_quoted_posts.rb
+++ b/db/migrate/20140715055242_add_quoted_posts.rb
@@ -3,7 +3,7 @@ class AddQuotedPosts < ActiveRecord::Migration
     create_table :quoted_posts do |t|
       t.integer :post_id, null: false
       t.integer :quoted_post_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :quoted_posts, [:post_id, :quoted_post_id], unique: true
diff --git a/db/migrate/20140716063802_add_badge_groupings.rb b/db/migrate/20140716063802_add_badge_groupings.rb
index bdcb02e8803..8ea63ed7797 100644
--- a/db/migrate/20140716063802_add_badge_groupings.rb
+++ b/db/migrate/20140716063802_add_badge_groupings.rb
@@ -4,7 +4,7 @@ class AddBadgeGroupings < ActiveRecord::Migration
       t.string :name, null: false
       t.string :description, null: false
       t.integer :position, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_column :badges, :badge_grouping_id, :integer
diff --git a/db/migrate/20140828172407_create_permalinks.rb b/db/migrate/20140828172407_create_permalinks.rb
index 5e4d9ce9b67..cc2e1a687f5 100644
--- a/db/migrate/20140828172407_create_permalinks.rb
+++ b/db/migrate/20140828172407_create_permalinks.rb
@@ -6,7 +6,7 @@ class CreatePermalinks < ActiveRecord::Migration
       t.integer :post_id
       t.integer :category_id
 
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :permalinks, :url
diff --git a/db/migrate/20140905171733_create_warnings.rb b/db/migrate/20140905171733_create_warnings.rb
index 90d38725b6e..c3da0e5c538 100644
--- a/db/migrate/20140905171733_create_warnings.rb
+++ b/db/migrate/20140905171733_create_warnings.rb
@@ -4,7 +4,7 @@ class CreateWarnings < ActiveRecord::Migration
       t.references :topic, null: false
       t.references :user, null: false
       t.integer :created_by_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     add_index :warnings, :user_id
     add_index :warnings, :topic_id, unique: true
diff --git a/db/migrate/20140925173220_create_user_fields.rb b/db/migrate/20140925173220_create_user_fields.rb
index 68c72452b60..5aad6efb8e5 100644
--- a/db/migrate/20140925173220_create_user_fields.rb
+++ b/db/migrate/20140925173220_create_user_fields.rb
@@ -3,7 +3,7 @@ class CreateUserFields < ActiveRecord::Migration
     create_table :user_fields do |t|
       t.string :name, null: false
       t.string :field_type, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20141223145058_create_csv_export_logs.rb b/db/migrate/20141223145058_create_csv_export_logs.rb
index 83291db28b0..870ba4d2125 100644
--- a/db/migrate/20141223145058_create_csv_export_logs.rb
+++ b/db/migrate/20141223145058_create_csv_export_logs.rb
@@ -3,7 +3,7 @@ class CreateCsvExportLogs < ActiveRecord::Migration
     create_table :csv_export_logs do |t|
       t.string :export_type, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20150108221703_group_managers.rb b/db/migrate/20150108221703_group_managers.rb
index 9c6e356ff20..512e2b19bc9 100644
--- a/db/migrate/20150108221703_group_managers.rb
+++ b/db/migrate/20150108221703_group_managers.rb
@@ -3,7 +3,7 @@ class GroupManagers < ActiveRecord::Migration
     create_table :group_managers do |t|
       t.integer :group_id, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :group_managers, [:group_id, :user_id], unique: true
diff --git a/db/migrate/20150213174159_create_digest_unsubscribe_keys.rb b/db/migrate/20150213174159_create_digest_unsubscribe_keys.rb
index 102146b6aa0..17d8c0d24ea 100644
--- a/db/migrate/20150213174159_create_digest_unsubscribe_keys.rb
+++ b/db/migrate/20150213174159_create_digest_unsubscribe_keys.rb
@@ -3,7 +3,7 @@ class CreateDigestUnsubscribeKeys < ActiveRecord::Migration
     create_table :digest_unsubscribe_keys, id: false do |t|
       t.string :key, limit: 64, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
     execute "ALTER TABLE digest_unsubscribe_keys ADD PRIMARY KEY (key)"
     add_index :digest_unsubscribe_keys, :created_at
diff --git a/db/migrate/20150318143915_create_directory_items.rb b/db/migrate/20150318143915_create_directory_items.rb
index 088bfba0d0d..111d4d4ba1b 100644
--- a/db/migrate/20150318143915_create_directory_items.rb
+++ b/db/migrate/20150318143915_create_directory_items.rb
@@ -8,7 +8,7 @@ class CreateDirectoryItems < ActiveRecord::Migration
       t.integer :topics_entered, null: false
       t.integer :topic_count, null: false
       t.integer :post_count, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :directory_items, :period_type
diff --git a/db/migrate/20150323234856_add_muted_users.rb b/db/migrate/20150323234856_add_muted_users.rb
index 8192d38284b..acdb020c7f1 100644
--- a/db/migrate/20150323234856_add_muted_users.rb
+++ b/db/migrate/20150323234856_add_muted_users.rb
@@ -3,7 +3,7 @@ class AddMutedUsers < ActiveRecord::Migration
     create_table :muted_users, force: true do |t|
       t.integer :user_id, null: false
       t.integer :muted_user_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :muted_users, [:user_id, :muted_user_id], unique: true
diff --git a/db/migrate/20150325190959_create_queued_posts.rb b/db/migrate/20150325190959_create_queued_posts.rb
index 9946a642b71..c511e8fcd22 100644
--- a/db/migrate/20150325190959_create_queued_posts.rb
+++ b/db/migrate/20150325190959_create_queued_posts.rb
@@ -11,7 +11,7 @@ class CreateQueuedPosts < ActiveRecord::Migration
       t.timestamp  :approved_at
       t.integer    :rejected_by_id
       t.timestamp  :rejected_at
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :queued_posts, [:queue, :state, :created_at], name: 'by_queue_status'
diff --git a/db/migrate/20150505044154_add_stylesheet_cache.rb b/db/migrate/20150505044154_add_stylesheet_cache.rb
index a23757ef973..d2034743f41 100644
--- a/db/migrate/20150505044154_add_stylesheet_cache.rb
+++ b/db/migrate/20150505044154_add_stylesheet_cache.rb
@@ -4,7 +4,7 @@ class AddStylesheetCache < ActiveRecord::Migration
       t.string :target, null: false
       t.string :digest, null: false
       t.text :content, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :stylesheet_cache, [:target, :digest], unique: true
diff --git a/db/migrate/20150727193414_create_user_field_options.rb b/db/migrate/20150727193414_create_user_field_options.rb
index 64e6e8ed378..abc3a1646c9 100644
--- a/db/migrate/20150727193414_create_user_field_options.rb
+++ b/db/migrate/20150727193414_create_user_field_options.rb
@@ -3,7 +3,7 @@ class CreateUserFieldOptions < ActiveRecord::Migration
     create_table :user_field_options, force: true do |t|
       t.references :user_field, null: false
       t.string :value, null: false
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20150802233112_add_post_stats.rb b/db/migrate/20150802233112_add_post_stats.rb
index 0ff42664da9..a59e081cb1b 100644
--- a/db/migrate/20150802233112_add_post_stats.rb
+++ b/db/migrate/20150802233112_add_post_stats.rb
@@ -8,7 +8,7 @@ class AddPostStats < ActiveRecord::Migration
       t.integer :drafts_saved
       t.integer :typing_duration_msecs
       t.integer :composer_open_duration_msecs
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :post_stats, [:post_id]
diff --git a/db/migrate/20150818190757_create_embeddable_hosts.rb b/db/migrate/20150818190757_create_embeddable_hosts.rb
index 1d4e1b0d46c..ce74f210824 100644
--- a/db/migrate/20150818190757_create_embeddable_hosts.rb
+++ b/db/migrate/20150818190757_create_embeddable_hosts.rb
@@ -3,7 +3,7 @@ class CreateEmbeddableHosts < ActiveRecord::Migration
     create_table :embeddable_hosts, force: true do |t|
       t.string :host, null: false
       t.integer :category_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     category_id = 0;
diff --git a/db/migrate/20151201035631_add_group_mentions.rb b/db/migrate/20151201035631_add_group_mentions.rb
index 4e3900387a2..5974ac2a5e2 100644
--- a/db/migrate/20151201035631_add_group_mentions.rb
+++ b/db/migrate/20151201035631_add_group_mentions.rb
@@ -3,7 +3,7 @@ class AddGroupMentions < ActiveRecord::Migration
     create_table :group_mentions do |t|
       t.integer :post_id
       t.integer :group_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :group_mentions, [:post_id, :group_id], unique: true
diff --git a/db/migrate/20151220232725_add_user_archived_messages_group_archived_messages.rb b/db/migrate/20151220232725_add_user_archived_messages_group_archived_messages.rb
index 9ec99718711..a9c067783ad 100644
--- a/db/migrate/20151220232725_add_user_archived_messages_group_archived_messages.rb
+++ b/db/migrate/20151220232725_add_user_archived_messages_group_archived_messages.rb
@@ -3,7 +3,7 @@ class AddUserArchivedMessagesGroupArchivedMessages < ActiveRecord::Migration
     create_table :user_archived_messages do |t|
       t.integer :user_id, null: false
       t.integer :topic_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_archived_messages, [:user_id, :topic_id], unique: true
@@ -11,7 +11,7 @@ class AddUserArchivedMessagesGroupArchivedMessages < ActiveRecord::Migration
     create_table :group_archived_messages do |t|
       t.integer :group_id, null: false
       t.integer :topic_id, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :group_archived_messages, [:group_id, :topic_id], unique: true
diff --git a/db/migrate/20160503205953_create_tags.rb b/db/migrate/20160503205953_create_tags.rb
index 6af853f7343..9c5eb491d06 100644
--- a/db/migrate/20160503205953_create_tags.rb
+++ b/db/migrate/20160503205953_create_tags.rb
@@ -3,20 +3,20 @@ class CreateTags < ActiveRecord::Migration
     create_table :tags do |t|
       t.string      :name,        null: false
       t.integer     :topic_count, null: false, default: 0
-      t.timestamps
+      t.timestamps null: false
     end
 
     create_table :topic_tags do |t|
       t.references :topic, null: false
       t.references :tag,   null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     create_table :tag_users do |t|
       t.references :tag,  null: false
       t.references :user, null: false
       t.integer    :notification_level, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :tags, :name, unique: true
diff --git a/db/migrate/20160527191614_create_category_tags.rb b/db/migrate/20160527191614_create_category_tags.rb
index 9ec7566e6f9..25ab47a468e 100644
--- a/db/migrate/20160527191614_create_category_tags.rb
+++ b/db/migrate/20160527191614_create_category_tags.rb
@@ -3,7 +3,7 @@ class CreateCategoryTags < ActiveRecord::Migration
     create_table :category_tags do |t|
       t.references :category, null: false
       t.references :tag,      null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :category_tags, [:category_id, :tag_id], name: "idx_category_tags_ix1", unique: true
diff --git a/db/migrate/20160602164008_create_tag_groups.rb b/db/migrate/20160602164008_create_tag_groups.rb
index e851ff39b95..8109ea81fb4 100644
--- a/db/migrate/20160602164008_create_tag_groups.rb
+++ b/db/migrate/20160602164008_create_tag_groups.rb
@@ -3,13 +3,13 @@ class CreateTagGroups < ActiveRecord::Migration
     create_table :tag_groups do |t|
       t.string :name,       null: false
       t.integer :tag_count, null: false, default: 0
-      t.timestamps
+      t.timestamps null: false
     end
 
     create_table :tag_group_memberships do |t|
       t.references :tag,       null: false
       t.references :tag_group, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :tag_group_memberships, [:tag_group_id, :tag_id], unique: true
diff --git a/db/migrate/20160606204319_create_category_tag_groups.rb b/db/migrate/20160606204319_create_category_tag_groups.rb
index 628f131ddc2..db6f52fc5eb 100644
--- a/db/migrate/20160606204319_create_category_tag_groups.rb
+++ b/db/migrate/20160606204319_create_category_tag_groups.rb
@@ -3,7 +3,7 @@ class CreateCategoryTagGroups < ActiveRecord::Migration
     create_table :category_tag_groups do |t|
       t.references :category,  null: false
       t.references :tag_group, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :category_tag_groups, [:category_id, :tag_group_id], name: "idx_category_tag_groups_ix1", unique: true
diff --git a/db/migrate/20160815002002_add_user_api_keys.rb b/db/migrate/20160815002002_add_user_api_keys.rb
index 0789781d87b..872365fab4b 100644
--- a/db/migrate/20160815002002_add_user_api_keys.rb
+++ b/db/migrate/20160815002002_add_user_api_keys.rb
@@ -9,7 +9,7 @@ class AddUserApiKeys < ActiveRecord::Migration
       t.boolean :write, null: false
       t.boolean :push, null: false
       t.string :push_url
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_api_keys, [:key], unique: true
diff --git a/db/migrate/20160905082248_create_web_hooks.rb b/db/migrate/20160905082248_create_web_hooks.rb
index f0f592507ac..b153522a168 100644
--- a/db/migrate/20160905082248_create_web_hooks.rb
+++ b/db/migrate/20160905082248_create_web_hooks.rb
@@ -10,7 +10,7 @@ class CreateWebHooks < ActiveRecord::Migration
       t.boolean :verify_certificate, default: true, null: false
       t.boolean :active, default: false, null: false
 
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20160905084502_create_web_hook_events.rb b/db/migrate/20160905084502_create_web_hook_events.rb
index 9f15520153c..72bba7f8f9e 100644
--- a/db/migrate/20160905084502_create_web_hook_events.rb
+++ b/db/migrate/20160905084502_create_web_hook_events.rb
@@ -9,7 +9,7 @@ class CreateWebHookEvents < ActiveRecord::Migration
       t.text       :response_body
       t.integer    :duration, default: 0
 
-      t.timestamps
+      t.timestamps null: false
     end
   end
 end
diff --git a/db/migrate/20170124181409_add_user_auth_tokens.rb b/db/migrate/20170124181409_add_user_auth_tokens.rb
index d7c785bb832..4e4b2c004b5 100644
--- a/db/migrate/20170124181409_add_user_auth_tokens.rb
+++ b/db/migrate/20170124181409_add_user_auth_tokens.rb
@@ -22,7 +22,7 @@ SQL
       t.boolean :legacy, default: false, null: false
       t.inet    :client_ip
       t.datetime :rotated_at, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_auth_tokens, [:auth_token]
diff --git a/db/migrate/20170313192741_add_themes.rb b/db/migrate/20170313192741_add_themes.rb
index 52905c86b76..528355efb57 100644
--- a/db/migrate/20170313192741_add_themes.rb
+++ b/db/migrate/20170313192741_add_themes.rb
@@ -9,7 +9,7 @@ class AddThemes < ActiveRecord::Migration
     create_table :child_themes do |t|
       t.integer :parent_theme_id
       t.integer :child_theme_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :child_themes, [:parent_theme_id, :child_theme_id], unique: true
diff --git a/db/migrate/20170322065911_create_topic_status_updates.rb b/db/migrate/20170322065911_create_topic_status_updates.rb
index 36f81a6fa8e..ece5ad5428c 100644
--- a/db/migrate/20170322065911_create_topic_status_updates.rb
+++ b/db/migrate/20170322065911_create_topic_status_updates.rb
@@ -8,7 +8,7 @@ class CreateTopicStatusUpdates < ActiveRecord::Migration
       t.boolean :based_on_last_post, null: false, default: false
       t.datetime :deleted_at
       t.integer :deleted_by_id
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :topic_status_updates, :user_id
diff --git a/db/migrate/20170328163918_break_up_themes_table.rb b/db/migrate/20170328163918_break_up_themes_table.rb
index 911584dbcdd..ef9943175f2 100644
--- a/db/migrate/20170328163918_break_up_themes_table.rb
+++ b/db/migrate/20170328163918_break_up_themes_table.rb
@@ -6,7 +6,7 @@ class BreakUpThemesTable < ActiveRecord::Migration
       t.string :name, null: false
       t.text :value, null: false
       t.text :value_baked
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :theme_fields, [:theme_id, :target, :name], unique: true
diff --git a/db/migrate/20170410170923_add_theme_remote_fields.rb b/db/migrate/20170410170923_add_theme_remote_fields.rb
index 95cb5d7e5c0..4e61feefeba 100644
--- a/db/migrate/20170410170923_add_theme_remote_fields.rb
+++ b/db/migrate/20170410170923_add_theme_remote_fields.rb
@@ -8,7 +8,7 @@ class AddThemeRemoteFields < ActiveRecord::Migration
       t.string :license_url
       t.integer :commits_behind
       t.datetime :remote_updated_at
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_column :themes, :remote_theme_id, :integer
diff --git a/db/migrate/20170512185227_create_topic_status_updates_again.rb b/db/migrate/20170512185227_create_topic_status_updates_again.rb
index aaa8ba70df2..30217d14cc8 100644
--- a/db/migrate/20170512185227_create_topic_status_updates_again.rb
+++ b/db/migrate/20170512185227_create_topic_status_updates_again.rb
@@ -10,7 +10,7 @@ class CreateTopicStatusUpdatesAgain < ActiveRecord::Migration
       t.boolean :based_on_last_post, null: false, default: false
       t.datetime :deleted_at
       t.integer :deleted_by_id
-      t.timestamps
+      t.timestamps null: false
       t.integer :category_id
     end
 
diff --git a/db/migrate/20170628152322_create_watched_words.rb b/db/migrate/20170628152322_create_watched_words.rb
index 212a3d2b9f6..b2ac8f72467 100644
--- a/db/migrate/20170628152322_create_watched_words.rb
+++ b/db/migrate/20170628152322_create_watched_words.rb
@@ -3,7 +3,7 @@ class CreateWatchedWords < ActiveRecord::Migration
     create_table :watched_words do |t|
       t.string  :word,   null: false
       t.integer :action, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :watched_words, [:action, :word], unique: true
diff --git a/db/migrate/20170717084947_create_user_emails.rb b/db/migrate/20170717084947_create_user_emails.rb
index eb6dc4980dc..ce9fd489c84 100644
--- a/db/migrate/20170717084947_create_user_emails.rb
+++ b/db/migrate/20170717084947_create_user_emails.rb
@@ -6,7 +6,7 @@ class CreateUserEmails < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.string :email, limit: 513, null: false
       t.boolean :primary, default: false, null: false
-      t.timestamps
+      t.timestamps null: false
     end
 
     add_index :user_emails, :user_id