Added psycopg2 to the dependencies to support postgres.

[syvwlch]

That got the site to work just fine with a local postgreSQL database with both the flask debug server and with heroku local.

Now it's time to try it in staging with the following plan:

• [x] push this code to staging

• [x] check everything still works

• [x] provision the postgres add-on

• [x] check everything still works

[syvwlch]

Review app and CI tests all looking good, will merge PR to push to staging.

[syvwlch]

Ok, waiting for master to auto-deploy to staging on Heroku

[syvwlch]

Ok, that worked.

[syvwlch]

Provisioned the postgres add-on in Heroku.

[syvwlch]

Everything still works, and I can see that rows have been added to the db!