* Stopped api key from assigning the 'Owner' role
refs #9865
We do not want api keys to be able to assign the Owner role to any other
key or user.
* Cleaned up Role model permissible method
no-issue
refs https://github.com/TryGhost/Ghost/issues/9865
- schema migrations
- adds `integrations` and `api_keys` tables
- inserts `integration` and `api_key` permissions and Administrator role relationships
- inserts `Admin Integration` role and permissions
- adds `Integration` model
- adds `ApiKey` model
- creates default secret if not given
- hardcodes associated role based on key type
- `admin` = `Admin API Client`
- `content` = no role
- updates `Role` model to use `bookshelf-relations` for auto cleanup of permission relationships on destroy
