Reference scope by same name as serialization scope

By default, the serialization scope uses current_user, and you can
now reference the scope as "current_user" in the serializer. If you
override the scope using "serialization_scope" in your controller,
it will use that method name instead.

lib/active_model/serializer/responder.rb

@@ -31,6 +31,7 @@ module ActiveModel
           if serializer
             serialization_scope = controller.send(:serialization_scope)
             options[:scope] = serialization_scope unless options.has_key?(:scope)
+            options[:scope_name] = controller.send(:_serialization_scope)
             options[:url_options] = controller.send(:url_options)
             render(given_options.merge(self.options).merge(:json => serializer.new(resource, options)))
           else
@@ -40,4 +41,4 @@ module ActiveModel
       end
     end
   end
-end
+end