The app name wasn't displayed correctly on the new relic dashboard.
Although `NEW_RELIC_APP_NAME` was set in `production.py`, the variable was not loaded *before* the newrelic agent was called.
Since the new relic agent is loaded at a very low level, NEW_RELIC_APP_NAME has to be set before django settings are imported.
- removed env.production and added a env.example that should be renamed to `.env` (not tracked by default)
- Refactored docker-compose.yml
* adding user to django, celeryworker, celerybeat so that we got rid of the `su` hack
* removed rabbitmq
- Refactored Dockerfile
- Refactored `entrypoint.sh` and added inline documentation
- Removed `su` hack from gunicorn.sh
- Added documentation
