public function logoutAction()
 {
     $auth = Zend_Auth::getInstance();
     if ($auth->hasIdentity()) {
         $info = Zend_Auth::getInstance()->getIdentity();
         $model = new Application_Model_DbTable_Usuarios();
         $usser = $model->traerdatoscliente($info);
         foreach ($usser as $user) {
             $id_usuario = $user->id_usuario;
         }
     }
     $model = new Application_Model_DbTable_Usuarios();
     $model->ultimoacceso($id_usuario);
     Zend_Auth::getInstance()->clearIdentity();
     $this->_redirect('index');
 }