Change middleware to support rails app in subfolders

If two applications run on the same domain

first_rails_app -> in http:://any_domain/
second_rails_app -> in http://any_domain/seccond_application

and the rails_panel was used then "meta_request" from the second app should be called.

To provide this the regular expression for the call-Method should listen on any "__meta_request" string on any page and the rails_panel should call the method on the current url path.