/**
  * creates a new local user controller
  * @return LocalUserController	LocalUserController instance
  */
 public static function create()
 {
     //check, if a LocalUserController instance already exists
     if (LocalUserController::$localUserController == null) {
         LocalUserController::$localUserController = new LocalUserController();
     }
     return LocalUserController::$localUserController;
 }
 public function setAccessGroup($username, $newAccessGroup)
 {
     //update user object
     $userobject = $this->getUser($username);
     $userobject->setAccessGroup($newAccessGroup);
     //change user in datastore
     $localUserController = LocalUserController::create();
     return $localUserController->changeUser($userobject);
 }