Fix counters on LocalSites for brand new review requests.

Counters on LocalSites weren't reliable for brand new review requests,
because at the point of save(), the local_site variable wasn't even set.
This meant that counters would get bumped on the main SiteProfile (the
one not tied to a LocalSite), but not on the one you'd expect from a
LocalSite. This manifested all kinds of wrong numbers on the dashboard for
LocalSites.

Fixed this by setting the local_site early. Added unit tests that
reproduced the problem.

Unit tests pass. The new test reproduced the exact problem I was seeing
rather well.