Add DB_OPTIONS to enable DBs with SSL

[angelnu]

Thanks for your work!

When trying to connect to connect to a postgres secured with TLS it failed to connect. With this PR it works:

docker run --rm -ti --name recipes -e DB_ENGINE=django.db.backends.postgresql_psycopg2 -e POSTGRES_HOST=recipes-db-postgres-cluster-postgres -e DB_OPTIONS='{"sslmode":"require"}' angelnu/recipes

[vabene1111]

thank you very much, i will review this and get it merged