Add Railo 4.2 release support

Added Railo 4.2 release to the cfml-ci config.  Not as straightforward as initially thought, as Railo changed the webroot in the Express install from `webapps/www` to `webapps/ROOT`.  Created a new railo-42plus helper script, although the only change is the `WEBROOT` envvar.  

Maybe a future cleanup will be to create a railo-helper-base for the common elements.

Closes #11