Confirm users own their Gituhb ID

Webmaster was notified of a situation where one user had 'claimed' the Github ID(by entering it into their account details) of another user.

Since we do test to make sure the Github ID entered doesn't already exist in our system, it seems reasonable to check that the person entering the ID actually controls that ID.

I don't know if doing a quick OAuth request, or some other API call to Github would be the answer.