This fetches the commit information from Github, so we don't have to tell
contributors to manually add themselves to the file with each PR. Also, we
now have an up-to-date list of translators.
Rather than just returning "permission denied", we can interpret this scenario
as a "failure to look up a user with that gym/user ID combo".
This should give users the information they need to self-recover, while not
leaking any other sensitive details.
Fixes: #585
