This adds support for specifying the "django.db.backends.postgresql"
django database engine, installing the required dependencies and setting
up the necessary configuration.
We're also adding a new package extras [postgresql] which will take care
of installing psycopg2 automatically.
This is self tested by integration tests which creates a postgresql
Docker container and runs the ara_api role configured to run against the
postgresql container. The tests are designed to run either locally or on Zuul.
Change-Id: I9bb7166d01c96d8b39361a55b1c9952de8fa9798
e32333930a