Quieter notifs

[kevinmcconnell]

@jzimdars I think this gets the notifications closer to what we need:

• If you're subscribed to a collection, you'll get notified when a new ticket is published in that collection.
• If you're watching a ticket, you'll get notified about all activity on that ticket.

To be watching a ticket you have to either have been involved in it (you get assigned, you comment, you created it, etc); or you can manually enable the notification bell for that ticket. But simply being subscribed to the collection isn't enough, on its own, to cause detailed notifications for all the tickets.