[TIMOB-13843] MobileWeb: Button.backgroundSelectedImage has no effect

*Steps to reproduce* 1. Run attached application 2. Click the button 3. See that the backgroundSelectedImage doesn't show *Expected result* The button will highlight to red *Actual result* Button's appearance doesn't change *Test case*

var win = Ti.UI.createWindow({
	backgroundColor : "#FFF"
});

var button = Ti.UI.createButton({
	title : 'Click',
	backgroundSelectedImage : 'testButton2.png',
	backgroundImage : 'testButton.png',
});

win.add(button);