Docker support

[mludvig]

Added Dockerfile to facilitate running of mlapi in a Docker container. It still relies on the standard development server and doesn't need uwsgi, Nginx, etc, like the themoosman fork.

Also adds support for $MLAPI_USER and $MLAPI_PASSWORD environment vars to enable creating the API user at the container start up. Also supports $MLAPI_SECRET_KEY and $MLAPI_ALPR_KEY env vars.

[pliablepixels]

Hey thanks for the PR. Isn't this already supported by moosman or is it different? I asked moosman to keep it on his own repo because I was not ready to support docker questions.

[mludvig]

This patch is a simple dockerisation of the repo, without further changes. Themoosman's repo is a fork that adds other changes, refactors to uwsgi, adds nginx, etc. It seems more like a diverging fork of your code - is he going to keep it up to date with your changes? In the long term I doubt so (I've seen forks before).

The Dockerfile included here simply facilitates building and running your version of mlapi in a container, i.e. in a 100% reproducible way without external dependencies.

I believe there won't be much to support in terms of docker questions :)

[connortechnology]

@mludvig I'd be happy to merge this if you'll update it.