/**
* Sign out user.
* Clears session and cookie
*
* @return boolean
*/
public static function signOut()
{
self::$id = 0;
self::$name = '';
self::$model = null;
self::$signed = false;
Request::setCookie("user_key", null);
if (session_id() !== '') {
session_destroy();
}
return true;
}