OBShapedButton Clickability Production

I have an app where this button is overlaying a map view.  In this scenario the button tends to lose its clickability and allow for the user to touch the map through the button.  After some debugging I found that the button seems to return an alpha of zero occasionally.  It seems to be that setting buttonImage and buttonBackground on each click runs the risk of checking a nil image.  I've added a few methods here that will detect a change in state and generate new images to check.  This should allow for more flexibility with the images.