Avoid deprecation warning about whitelist_attributes in rails 4

config/application.rb

@@ -128,10 +128,11 @@ module Discourse
     config.ember.ember_location = "#{Rails.root}/vendor/assets/javascripts/production/ember.js"
     config.ember.handlebars_location = "#{Rails.root}/vendor/assets/javascripts/handlebars.js"
 
+    unless rails4?
       # Since we are using strong_parameters, we can disable and remove
       # attr_accessible.
       config.active_record.whitelist_attributes = false
-
+    end
 
     require 'plugin'
     require 'auth'