Add automatic Docker build

[maxmeyer]

If either #27 or #66 are merged, please setup an automatic "Docker build" on hub.docker.com. BTW: #66 assumes, that your account on hub.docker.com is "radhifadlillah" - lower case is required by docker.

[RadhiFadlillah]

Hi @maxmeyer thanks for the PR.

I've never use Docker before, that's why I've put off merging those PRs while I learning at least the basic of Docker. It should be merged soon though.

[maxmeyer]

@RadhiFadlillah Thanks for the feedback. Feel free to ask if something is unclear or you get stuck.

[RadhiFadlillah]

Done by PR #66.