Add tap intercept view instead of tap GR

In iOS 6+, gesture recognizers were fiddled with to allow them to play nice
with buttons. This means that the tap gesture recognizer was letting taps fall
through to the content view controller, leading to some mildly annoying
behavior.

The fix is to add a touch intercepting view to the contentView that already
has the tap gesture recognizer added to it. This view will intercept all touch
events, keeping them from falling through to the content view controller.