Social website idea: add review marking and user ranking to expo and/or ACKs

In order to encourage expo users to review each other's package, it would be interesting to add "review marking" and "user ranking" features to expo.

When a maintainer gets reviews, he would give them a mark ("not useful" .... "very useful"), and the reviewers would get points. It would then be possible to sort upload requests by the points of their uploaders. So people would be encouraged to review other packages, to earn points and get their packages more visible.

Something similar that could be implemented is "ACKs". A non-DD could review a package, say that everything looks perfect, and then we could sort packages based on ACKs. That could create a "review" economy.

Originally reported by @lucas at https://alioth.debian.org/tracker/index.php?func=detail&aid=313252&group_id=100127&atid=413115