removed t and f 's from group model

removed t and f 's from user model as mentioned in #919

removed t's and f's from category model

app/models/category.rb

@@ -34,9 +34,9 @@ class Category < ActiveRecord::Base
   scope :secured, ->(guardian = nil) {
     ids = guardian.secure_category_ids if guardian
     if ids.present?
-      where("categories.secure ='f' or categories.id in (:cats)", cats: ids)
+      where("NOT categories.secure or categories.id in (:cats)", cats: ids)
     else
-      where("categories.secure ='f'")
+      where("NOT categories.secure")
     end
   }
 

app/models/group.rb

@@ -38,11 +38,11 @@ class Group < ActiveRecord::Base
 
     real_ids = case name
                when :admins
-                 "SELECT u.id FROM users u WHERE u.admin = 't'"
+                 "SELECT u.id FROM users u WHERE u.admin"
                when :moderators
-                 "SELECT u.id FROM users u WHERE u.moderator = 't'"
+                 "SELECT u.id FROM users u WHERE u.moderator"
                when :staff
-                 "SELECT u.id FROM users u WHERE u.moderator = 't' OR u.admin = 't'"
+                 "SELECT u.id FROM users u WHERE u.moderator OR u.admin"
                when :trust_level_1, :trust_level_2, :trust_level_3, :trust_level_4, :trust_level_5
                  "SELECT u.id FROM users u WHERE u.trust_level = #{id-10}"
                end

app/models/user.rb

@@ -60,7 +60,7 @@ class User < ActiveRecord::Base
 
   scope :admins, ->{ where(admin: true) }
   scope :moderators, ->{ where(moderator: true) }
-  scope :staff, ->{ where("moderator = 't' or admin = 't'") }
+  scope :staff, ->{ where("moderator or admin ") }
 
   module NewTopicDuration
     ALWAYS = -1