First cut at integration tests

[gordonje]

• [x] Create a simple unit test, using Django's test suite, that checks for an ok status response from the admin login view.
• [x] Define travis settings (check out what we did on TweetsToText as an example)
  • [x] Include Postgres
  • [x] Check for other system dependencies we need (e.g., stuff for Pillow)
  • [x] With pushes to master, also call zappa update prod
  • [x] Be sure to include secure AWS credentials for the IAM user associated with this project
  • [x] Be sure to include encrypted zappa_settings.json and secrets.cfg