fix query port for rust and 7d2d protocols

Hi!
Thank you for support "Rust" and "7 Days to Die" games.
But it's not working for me.
Because I think there was a bug with query ports for those games.
query_port = port + 1, 
but you used  
```php
$this->port_client(($this->port_client() - 1));
```

I fixed it and test this changes. Now rust and 7d2d servers working fine. I take servers for test from http://www.gametracker.com//search/rust/ and http://www.gametracker.com//search/7d2d/ 
Please take my pull request.
Thank you!