[TIMOB-13734] iOS: ImageView - changes image aspect ratio when scaling

Our [documentation](http://docs.appcelerator.com/titanium/3.0/#!/guide/Images_and_ImageView_APIs-section-29004912_ImagesandImageViewAPIs-TheImageView) says that when you have height and width set on an imageView, it should scale image without changing its aspect ratio. This worked correctly in 2.1.4.GA, but is stretching the image as of 3.0.0.GA (see attached screenshot).

Steps to reproduce:

1. Run the code below with 3.0.0.GA or 3.0.1.GA. 2. Notice that the image is stretched 3. Run the code below with 2.1.4.GA 4. Notice that the image is not stretched as seen in the [documentation](http://docs.appcelerator.com/titanium/3.0/#!/guide/Images_and_ImageView_APIs-section-29004912_ImagesandImageViewAPIs-TheImageView).

var win = Ti.UI.createWindow({
	backgroundColor: 'white'
});
win.open();

var iv = Ti.UI.createImageView({
	image: "KS_nav_ui.png",
	height: 200,
	width: 50,
	backgroundColor: 'yellow'
});
win.add(iv);