refs: https://github.com/TryGhost/Team/issues/510
- Ghost config always uses camelcase. This was incorrectly implemented with snake case originally
- Swap to use camelCase by default, which is desirable, but support both
- It's really easy to support both in the loader and isLimited check, so we do this to stop ourselves tripping on this later
refs: https://github.com/TryGhost/Team/issues/510
- we need to make sure we take into account any invites that could be accepted at any time
- this counts all invites for non-contributor roles as well as all users who aren't contributors
- this should stop there being loop holes to inviting staff users