fixes #11657 - show link to add a user again if form was canceled

plugins/UsersManager/angularjs/manage-users/manage-users.controller.js

@@ -163,6 +163,7 @@
                 piwikHelper.hideAjaxError();
                 $(this).parents('tr').remove();
                 $('.add-user').toggle();
+                self.showCreateUser = true;
             });
         };