Add ip to "good" return code

Hey - great little piece of software you wrote there! I just wanted to point out that some built-in DDNS clients require a more accurate "good" response. Namely all AVM router (FritzBox) which are quite common in Europe require the sucess response to also include the current IP. So a small change in line 85 of Server.php to $this->returnCode('good '.$this->myIp); did the trick for me. I have no idea if such a change breaks any other clients but I would suggest to include the change in your code.

Thanks for your suggestion! I'll check that!

My AVM router (FritzBox) seems to not require the IP address in the "good" response, but I will have a look at it.