Throttle view notifications

Only post the notification per loader instance, per raw contact.
This means:
- When you open a contact card, we post the notification for the contact.
- If the contact card reloads itself, we do *not* post the notification,
  as we use the same loader instance for this.
- (If you close the contact card and re-open it, we do post the notifictaion,
  of course)
- If you're opening cotact card, and the current cotnact got a new raw contact
  as a result of background sync, we *do* post the notification for the new
  raw contact, not not for existing raw contacts.

Bug 5153847

Change-Id: Id8ef9ece7f2aa991d0c625072b7c58f839e05bb3