UC-21 Disable/remove push notifications from facebook Connect

The functionality for push notifications for Facebook connect has been broken for some time (see UC-20). This ticket cleans up all of the broken Facebook Connect code which had to do with pushing notifications, and removes all the references to that feature on the user facing side.

Ticket: https://wikia-inc.atlassian.net/browse/UC-21
I consulted Song and he updated this message beyond just removing the sentence regarding user preferences (in case you were wondering why there were additions to this message). He said it reads more clearly this way.