docker-compose.yml database settings

[scuerda]

The docker-compose.yml pulls postgres but the standard config uses sqlite.

Might be helpful to use a .env and something like django environ to implement 12-factor-style configuration.

I'm happy to submit a pull request for this if there is interest.

[alchenist]

@scuerda A PR would be great! Moving environment-specific config out of settings.py sounds like a fine idea.

[scuerda]

Sounds good. I'll put something together in next day or so.