Most build tools (i.e., the CircleCI Orbs) expect a Dockerfile in the
repo root. Rather than have to configure an exception everywhere, put it
where most people/tools expect it to be.
Dockerfile is now a single multi-stage build that relies on a Python 3.7
base image.
Notes:
- This builds uWSGI with a `pip install` because the Alpine vendored
uWSGI is built against Python 3.6.
- Adds a docker-compose file that can be used for testing that the build
works. It is not usable for development purposes because it creates a
static copy of the application.
