Publish apache/yetus docker images on hub.docker.com

In order to provide better support for CI services (Travis, Gitlab CI, etc), the yetus Docker images should get published. We should also provide documentation on how to use it standalone. e.g.,:

"docker run -it -v /mysource:/mysource -v /myoutput:/myoutput apache/yetus qbt --basedir=/mysource --patch-dir=/myoutput --plugins=all"

Or whatever.