* Simplified db controller permissions options
The existing objects were confusing because they did the same thing as
setting permissions to true, but gave the impressions that something
special was happening/required.
* Added DB Backup Integration Role
This will allow us to assign certain api_keys this role, in order to
automate db backups
* Allowed admin api_keys to have configurable roles
This will allow keys for the admin api to do customised things such as db export
* Added ghost-backup integration to fixtures
* Added migrations for DB Backup Integration and role
