JCLOUDS-750 Start using AutoValue on Docker.

this builds on https://github.com/jclouds/jclouds/pull/586 and depends on it.
Can you prove that by capturing test data, andrea? As we drift towards
latest version of docker api, I don't want to maintain 2 objects or a
custom type adapter because of something on an earlier version.

Ex. can you prove that the latest version of docker returns ImageId yet
requires you to serialize the field as imageId (or similar)?