(Bug 4176) Support notifs should include username

Notifications of new support requests now contain the username or
(for logged-out requests) name provided by user. Notifications of
follow-ups to support requests now contain the username of the
person who left the response. I do not allow for anonymous follow-
ups because as far as I can tell they can't happen.
Merge pull request #427 from kaberett/bug4176-support-username

Bug4176 support notifications should include username