use script_Name to get /logout url

wcs/admin/menu.ptl

@@ -32,7 +32,7 @@ def user_info [html] ():
         user = storage.get_storage().retrieve('users', session.user)
     except KeyError:
         return ''
-    logout_url = quixote.get_request().get_path(-1).replace(str('/admin'), str('/logout'))
+    logout_url = quixote.get_request().environ['SCRIPT_NAME'] + '/logout'
     """<ul class="user-info">
   <li class="ui-name">%s</li>
   <li class="ui-logout"><a href="%s">%s</a></li>