Users who lose their sponsor when the sponsor leaves the Organisation

[rtyley]

There should probably be an account requirement that gets played against users that have been sponsored, but by users who have left the organisation. The point of sponsorship is to ensure there's always someone responsible for any given user account - the person you can ask: "Does this person still work for us?!" - and this breaks down when senior staff leave, taking their workplace/staff knowledge with them.

The algorithm would be something like:

• do a git blame on users.txt
• use this to construct a map of user -> sponsor(s?) ...note this probably requires mapping from email to github username on the sponsor?! Instead, do scrape the github blame page?!?
• any user that doesn't have a sponsor currently in the organisation, needs to get an issue raised against them, asking them to get a new sponsor to add a comment to the relevant line in users.txt so they now assume responsibility for that user.