Added support for starring groups and review requests. Starring a group puts it on your dashboard under a "Watched Groups" list, which is useful when you want to keep track of a group but don't want the group's review requests appearing under your Incoming Reviews list or sending you e-mails.

Starring a review request puts it in your Starred Reviews list and sends any e-mails your way. This is useful if you're not a reviewer of a review request but want to keep track of what's going on with it without having to get involved.

Tested that starring and unstarring works in each area, and that they appear on the dashboard.