Fix: BulkUpdate when removing a Draggable Object

https://github.com/Famous/famous-angular/issues/185

When $destroy is called on a Draggable, from deleting an item in a ng-repeat or from ui-router. It appears that it goes through $destroy without testing if it's a modifier so it tries to renderNode.unpipe(EventHandler). I've corrected this by testing it again before updating the pipes.