JCLOUDS-750 Start using AutoValue on Docker.

this builds on https://github.com/jclouds/jclouds/pull/586 and depends on it.
@gk5885 @eamonnmcmanus @cgruber FYI: I updated our custom gson integration so that it can recognize factory methods and pluck the names off. Would love to replace this with generated code at some point, but it is currently reflective.