public static function registerIncludeRoot($root=null)
  {
    if(is_null($root)){
      $root = dirname(__FILE__).DIRECTORY_SEPARATOR.'..'.DIRECTORY_SEPARATOR.'..'.DIRECTORY_SEPARATOR;
    }
    if(!in_array($root, self::$frameworkRoots)){
      self::$frameworkRoots[] = $root;
      return true;
    }
    return false;
  }