Add individual contribution statistics to the review page

[Jorge Castro]

I'd like to show off people who are awesome, so on the review queue page how about something like 2 columns, "Top Reviewers this month/alltime" and "Top charm contributors this month/all time" and then a list of names.

For bonus points find their gravatar/lp picture/github picture so we can put a name to the people. That way every time there's a review people are reminded of the work their friends are doing.

Also make the the information available via json or something so we can put the contributors on the hall of fame, our blogs, etc.

We also might want to consider just making it a separate page so we can add other statistics.