WIP: Wire up the database

The database is created by the `services` virtual machine because CloudFormation creates the database inside RDS.

- [ ] Inject database information into the environment for the Django settings file
- [ ] Sort out https://github.com/azavea/ansible-nginx/pull/3 so that test runs don't fail

Will eventually attempt resolve https://github.com/azavea/nyc-trees/issues/31.
``nyc_trees`` lines up with the application name, and is a good candidate for database name.