Change the AutoValue pom.xml so that it uses the Maven shade plugin to i...

Change the AutoValue pom.xml so that it uses the Maven shade plugin to include all dependencies in the generated jar, and to rename most of them. This is intended to address https://github.com/google/auto/issues/156.
As written, this overwrites auto-value-1.0-SNAPSHOT.jar with the shaded version. I think that's what we want. Is there a problem?