fix page blank for 403 forbidden.

app/controllers/admin/object_auths_controller.rb

@@ -91,7 +91,8 @@ private
 
   def check_if_user_can_do_object_auth
     unless  check_permission(:manager)
-      render :nothing => true, :status => 403 
+      #render :nothing => true, :status => 403 
+      redirect_to '/'
     end
   end
 end