public function executeSignout(sfWebResponse $request)
 {
     $this->getUser()->signOut();
     $signout_url = sfConfig::get('app_sf_guard_plugin_success_signout_url', $request->getReferer());
     $this->getUser()->setFlash('notice', 'U bent uitgelogd');
     $this->redirect('' != $signout_url ? $signout_url : '@homepage');
 }