fix preview bug only happen when production

vendor/built_in_modules/announcement/app/controllers/panel/announcement/back_end/bulletins_controller.rb

@@ -18,7 +18,7 @@ class Panel::Announcement::BackEnd::BulletinsController < OrbitBackendController
     bulletin = Bulletin.new params
     @preview_obj = bulletin.to_preview
     @preview_obj.save
-    render '/shared/preview/preview.html.erb'
+    render '/shared/preview/preview.html.erb', :layout=>false
   end
 
   def index