Fix site preference openness problem

app/controllers/application_controller.rb

@@ -18,7 +18,7 @@ class ApplicationController < ActionController::Base
   helper_attr :site_valid_locales
 
   def check_backend_openness
-    if !Me.backend_openness_on
+    if Site.first.backend_openness_on
       redirect_to '/users/sign_in'   if not (authenticate_user! and is_member? )
     end
   end