Allow users to opt-out from the ActionController extensions

lib/action_controller/serialization.rb

@@ -29,6 +29,11 @@ module ActionController
 
     include ActionController::Renderers
 
+    class << self
+      attr_accessor :enabled
+    end
+    self.enabled = true
+
     included do
       class_attribute :_serialization_scope
       self._serialization_scope = :current_user