Add dockerfile with ngxin+uwsgi, volumes and optional S3 storage

[fluential]

Adressing all comments from #13

• Removed supervisord.ini file as this comes by default from the original image https://github.com/tiangolo/uwsgi-nginx-docker/blob/master/docker-images/supervisord-alpine.ini and we don't need to modify it as I originally thought

This implements

• S3 persistent storage so its possible to safely start and stop container, it does restore on startup + backup after 30s delay, according to a schedule
• uwsgi+nginx for much better performance

For yet better performance consider using ASGI frameworks instead of WSGI. If you still need more +400% performance for this uwsgi+nginx flask app consider using this image https://github.com/tiangolo/meinheld-gunicorn-flask-docker 😎

[fluential]

Thanks for update, to be honest I don't want to spend more time on this, I will not be submitting more changes. I'll leave it with you.

[brentvollebregt]

That's ok @fluential, thank you for your contribution. I will try to look into the questions/actions I have added and get this in when they're answered.