Fix for rotation issues on iOS8

Returning true in ShouldAutorotate() caused exception when game orientation was Portrait or PortraitDown.

This fix keeps fix for landscape orientation on iOS8.

To make this work properly, I had to add auto detection of SupportedOrientation, because first `iOSGameViewController.ShouldAutorotate` is called before developer has a chance to set SupportedOrientations. 

Now, developer doesn't have to set SupportedOrientation in code, cause it'll be obtained from Application settings.

Also issue when both Portrait and Landscape mode are enabled has been fixed here.