Issue: No Contributor List

This bug was found by mangus580. Essentially 3 separate users had performed modifications to an article, but the "Contributors" list never appeared, and the "Edited by" info never appeared.

This occurs when all of your contributors (except perhaps 1) have only a Primary Usergroup and no Secondary Usergroups (Member Groups). Without any membergroups, an empty value is used, which VaultWiki synonimizes with the user being a guest or having been banned.

Fixed in the next build by ignoring empty membergroupids.