Ability to specify config file from the command line

The standalone server and ProcessController/HostController main methods should take a switch specifying the name of the config file to use (files, in the case of ProcessController/HostController), with "standalone.xml", "host.xml" and "domain.xml" being the default.

This allows things like devs having different standalone mode profiles configured and switching between them, multiple host configs in a production distribution with environment variables on different hosts causing the right one to be used, etc.