use autoload for responder

lib/simple_controller.rb

@@ -5,9 +5,9 @@ require 'responders'
 require 'ransack'
 require 'inherited_resources'
 require 'pundit'
-require 'simple_controller/responder'
 
 module SimpleController
   autoload :VERSION,            'simple_controller/version'
   autoload :BaseController,               'simple_controller/base_controller'
+  autoload :Responder,               'simple_controller/responder'
 end