fix the view size problem

[yangchenlarkin]

MTStatusBarOverlay will fill all my screen when it appears. That is because [UIWindow init] will set it's size (MTStatusBarOverlay.frame.size) to screen size, after it calls initWithFrame method. So I changed the code like this. That means all the code in [MTStatusBarOverlay init] will be called after [UIWindow init]. This did solve the problem.

BTW, I found this problem in iOS 9.3.4