Easier environment setup with Fabric

I've been working on adding fabric support for a quicker dev environment setup. It's not quite ready, but it's far enough along that I'd like to get feedback before I continue too far down this road.

Some things that I'm still working on:

- `fab run` and `fab run:development` don't run start ngrok
- `fab run:production` doesn't touch iptables or init the models
- `fab test` doesn't exist yet (bit confused as to whether it's `test.py` or `old/test_server.py`)