////
// Standard Tab Controller with: 
//   Save model on exit
//   Status property associated model
//   Model save actions
//
App.StandardTabController = Em.ObjectController.extend(App.ControllerObjectSaveMixin, App.ControllerObjectStatusMixin, App.SaveOnExitMixin, {
    hint: null
});
////
// Standard Tab Controller with: 
//   Save model on exit
//   Status property associated model
//   Model save actions
//
App.StandardTabController = Em.ObjectController.extend(App.ControllerObjectSaveMixin, App.ControllerObjectStatusMixin, App.SaveOnExitMixin, {});

Update controllers.js