Reject ssh keys that break gitolite
Created by: dosire
Without this code an invalid ssh key could break Gitlab for everyone. For example an ssh key with a space in the middle would pass validation but would give errors in each Gitolite operation.
The errors would look like:
remote: FATAL: fingerprinting failed for 'keydir/admin_local_host_1348232546.pub'
This PR solves this by fingerprinting as part of the validation process.
These commits are not squashed because we already needed to merge them into the gitlab.com repository to prevent this problem.