Death to Spork! Death! Death!
rails g scaffold notifications.
added cancan abilities for reading notifications
removed unwanted methods from controller
a bit of test cleanup
Removed "notification type" since WAGNI (yet)

We figured that doing without it was more like the simplest thing that
could possibly work.

Note that we edited the migration in place after rolling back.  This
would cause problems if anyone had downloaded the code from pozorvlak's
repo the other day and run it, but we're assuming they didn't (since
they wouldn't have got anything interesting out of it anyway.)
removing unwanted new/edit stuff for notifications
comments now generate notifications
changed to/from to recipient/sender
prettified notifications inbox etc
Show unread notifications as bold

The view here isn't as DRY as we'd like, but all the options were kind
of ugly, and this one was easiest.
added inbox link and count to nav
don't send notifications to yourself
Merge branch "notifications".