Fix #233 reproducible builds

[agentgt]

This just makes the maven artifact compare work. To really test you will need to try https://github.com/jvm-repo-rebuild/reproducible-central with different machines and docker images (yes all of these can make a difference).

I also recommend if you use any plugins to require -Duser.timezone=UTC at release time.

You can check out JStachio root pom in the enforcers and profiles to see how I did it as this PR does not have all the safety guards in.