Convert FailureNotificationResource, StatusPayResource and PreparePayResource to DRF (bug 910602, bug 910612 and bug 910609)

https://bugzilla.mozilla.org/show_bug.cgi?id=910602
https://bugzilla.mozilla.org/show_bug.cgi?id=910612
https://bugzilla.mozilla.org/show_bug.cgi?id=910609

Doing all 3 in the same pull request as they are in the same file and I'm tired of fixing conflicts with myself. They are all pretty small.