Zurich add internal notes

Closes mysociety/FixMyStreet-Commercial#405

Note this is based on the changes in #549 

A mixed bag of changes. Some improving the test running (for example Travis should now run the Zurich tests) and some troubleshooting notes.

Once merged the following command should be run to convert internal_notes stored directly on the problems into comments.

``` bash
./bin/cron-wrapper bin/zurich/convert_internal_notes_to_comments $USER_ID_TO_ASSIGN_NOTES_TO
```

See the comments in `bin/zurich/convert_internal_notes_to_comments` for details.