Fixes #317. AV::Rendering module should be included after AC::ApiRendering

Author: Jorge Bejar and Santiago Pastorino

lib/jbuilder/railtie.rb

@@ -9,16 +9,18 @@ class Railtie < ::Rails::Railtie
         require 'jbuilder/dependency_tracker'
       end
 
-      if app.config.respond_to?(:api_only) && app.config.api_only
+      if Rails::VERSION::MAJOR >= 5
         module ::ActionController
           module ApiRendering
             include ActionView::Rendering
           end
         end
 
         ActiveSupport.on_load :action_controller do
-          include ActionController::Helpers
-          include ActionController::ImplicitRender
+          if self == ActionController::API
+            include ActionController::Helpers
+            include ActionController::ImplicitRender
+          end
         end
       end
     end