Config server with settings

Added setting interface (ServerSettings and ServerInternalSettings) for server to access its configuration properties.

Enabled to obtain a server property with Config.get + property settings. Replaced the previous Apache Configuration + constant string property-accessing-pattern. 
While technically a safe thing to do, I don't feel entirely comfortable removing all these things in here. People are still using this API, unfortunately. I'd be more comfortable if we deprecated these things and added a note that they will be removed in 3.0.0