Added the ability to delete or clear notifications.
* A "Clear all" button deletes them all (with confirmation)
* A "Remove" button on individual notifications (one confirmation per
page load, so you can remove several without too much tedium)
Fix some things regarding private photo notifications:
* When notifying your existing grants about a new upload, only users who
opt-in for Explicit are notified about Explicit private pictures.
* When revoking private grants, clean up the "has uploaded a new private
photo" notifications for all of your pics from their notification
feeds.
fdc410c9f1