Fixes #142 - Replaced original pan gesture with the edge swipe gesture & tracking pan in same manner as iOS 6.  Edge Panner should not trigger on UINavigationBar per how it operates elsewhere in iOS 7.
Cleaned up (removed) code that was either commented out or no longer fired due to other code being commented out.
Fixes #142 - Since UIScreenEdgePanGestureRecognizer is in fact a UIPanGestureRecognizer, I simplified the solution to use a subclass instead of a separate gesture property.