remove deprecated split view controller delegate methods

in iOS 8, the primary view controller ([svc.viewControllers firstObject]) is
always hanging around. it is set to the delegate so that it can decide how
to handle the difference between a collapsed and expanded experience. at
this stage, the secondary view controller is always discarded. this isn't
what the intended functionality is, rather if an item is selected then the
collapsed view should show the secondary view controller collapsed into the
primary.
detail view on top when collapsing if item is selected