fix error

lib/tasks/detect_sites.rake

@@ -92,7 +92,7 @@ namespace :create_site do
             end
           end
         end
-        SiteConstruct.where(:domain_name.in => ['','localhost','127.0.0.1']).destroy
+        SiteConstruct.where(:domain_name.in => [nil,'','localhost','127.0.0.1']).destroy
         @thread.update(:status=>@thread.status.merge({"status"=>"finish"}))
       rescue => e
         puts [e,e.backtrace]