[WFLY-3675] Remove mod_cluster ContextHost and Proxy classes and use res...

...olveModelAttribute() instead

https://issues.jboss.org/browse/WFLY-3675

Goodbye hacky classes.
You can use (Short.MAX_VALUE - Short.MIN_VALUE) to represent max unsigned short.  Using constants makes the literal value look less arbitrary - but now I'm really nitpicking...