Add docker support

[hugglesfox]

Create docker images for Aardwolf.

Todo before merging:

• [x] Dockerfile
• [x] docker-compose.yml
• [x] docker-entrypoint.sh
• [x] Documentation

Some things to consider (in order of usefulness):

• [ ] Aardwolf logging to STDOUT
• [ ] Automatic Travis docker image builds
  • [ ] amd64
  • [ ] arm64
• [ ] Deployment to Docker Hub
• [ ] Image scanning

[hugglesfox]

FYI I had to change my pgp key thus the commits are no longer verified

[BanjoFox]

womp womp