[TIMOB-20282] Windows: ProgressBar default layout should be SIZE, not FILL

According to [Transitioning to the New UI Layout System](http://docs.appcelerator.com/platform/latest/#!/guide/Transitioning_to_the_New_UI_Layout_System), the default layout of ProgressBar should be Ti.UI.SIZE, not Ti.UI.FILL. For instance following example should show green background only under the progress bar & text, and it should not fill parent view.

var pb = Ti.UI.createProgressBar({
    min: 0,
    max: 10,
    value: 0,
    color: 'blue',
    backgroundColor: 'green',
    backgroundDisabledColor: 'gray',
    message: 'Downloading 0 of 10'
});
var win = Ti.UI.createWindow();
win.add(pb);
win.open();
pb.show();