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. 
Same thing here - this is awesome, but we also, annoyingly, need to keep the old Configuration interface injectable. As such, we should have an additional line here like:

    add( providerForSingleton( new ConfigWrappingConfiguration( config ), Configuration.class );

This is because unmanaged extensions have access to these injectables, so removing the ability to inject the old Configuration interface may break existing extensions during runtime.