Functional tests

This adds a basic 'happy path' functional test. This tests the general flow of the application from source submitting a message to journalist downloading and reading it.

A few todo's:
- Add phantomjs to setup_ubuntu and HACKING
- Possibly organize tests into their own folder as we now have a couple different test files. test.py is getting pretty big and could even be split up into more files.
- Possibly add more functional tests (but not too many)