Feature/84 ip address from proxy

There is no manual, in fact manuals are not code and just another thing to maintain. Just like the API documentation for janus, I'd rather keep it as close to the code as possible so it doesn't get out of date.
In fact this has always been the promise of the EngineBlock application.ini, that it is not only the defaults but the complete documentation for configuring OpenConext EngineBlock: https://github.com/OpenConext/OpenConext-engineblock/blob/feature/84-ip-address-from-proxy/application/configs/application.ini#L10