refs https://github.com/TryGhost/Ghost/pull/9592
- we add bookshelf-relations step by step if we need it
- with https://github.com/TryGhost/Ghost/pull/9592 we have rewritten the test env to use Bookshelf
- this is important for our new url service
- because the service is listening on model updates and updates the urls based on the model events
- so with moving to Bookshelf, we need any easy way to add relations
- the test env inserts test fixtures
- it adds permissions and each permission get's roles attached
- `models.Permission.add({roles: [...]})
