added server name, for creating url rules

Added server name like in [`yii2-advanced`](https://github.com/yiisoft/yii2/blob/master/apps/advanced/frontend/tests/_bootstrap.php#L23), this can be needed when user creating urls, for example in `yii2-advanced` it is used in mail [message](https://github.com/yiisoft/yii2/blob/master/apps/advanced/common/mail/passwordResetToken.php#L9).