public static function userHasRole($role , $username = null)
	{
		if ( is_null( $username ) ) $username = self::getCurrentUsername();
		if ( is_null( $username ) ) return false;
		if ( ! self::userExists( $username ) ) return false;
		if ( in_array( 'admin' , self::$auth['users'][ $username ]['roles'] ) ) return true;
		return ( in_array( $role , self::$auth['users'][ $username ]['roles'] ) );
	}