[TIMOB-8433] iOS: Ti.UI.ImageView does not follow explicit sizing

Currently, iOS image views do not obey explicit sizing instructions for percentage measurements (and possibly others). For example, when we have an image of 300 x 419 at "50%" embedded in a parent view of 200, we do not see the behavior of the image view which would be expected (it measures 100 x 100, with image stretching).

var win = Ti.UI.createWindow();

var parent = Ti.UI.createView({
	width:200,
	height:200,
	backgroundColor:'red'
});
var child = Ti.UI.createView({
	width:"50%",
	height:"50%",
	backgroundColor:'blue'
});
var image = Ti.UI.createImageView({
	width:"50%",
	height:"50%",
	image:'images/corkboard.jpg'
});

parent.add(child);
parent.add(image);
win.add(parent);
win.open();

Pass

---- The blue view should not be visible, since it has the same dimensions as the image view, which should overlay it.