Release v3.0.0

I prepared the project to release version 3.0.0. As for this version you can only download the zip file I had to change the pom a bit. It would be nice if you could release version 3.0.0, upload it to the official mvn repo and then revert my changes so the next version 4.x can be build. I have no clue if that is the way how to add older and not yet released versions. I normally do not relese version 3 before version 4 :)