Publish the flink docker container to the docker registry

There's a dockerfile that can be used to build a docker container already in the repository. It'd be awesome to just be able to pull it instead of building it ourselves.
The dockerfile can be found at https://github.com/apache/flink/tree/master/flink-contrib/docker-flink
It also doesn't point to the latest version of Flink which I fixed in https://github.com/apache/flink/pull/1366