[RZTransitionsManager setInteractionController:...] doesn't return what it promised

[mr-fixit]

The header doc for [RZTransitionsManager setInteractionController: fromViewController:toViewController:forAction:] claims it'll return a unique key to reference the pairing, but...

1. due to a shadowed variable bug, it always returns nil
2. the way it's currently written, there is no 'unique key' to return. It adds as many objects to the map as there are bits set in the action.