Some modernization and possible fix for #11

1. Hides the status bar on iOS 7; simply adds the `prefersStatusBarHidden` method to the RootViewController.
2. Fix for #11 
3. Ups deployment target to iOS 5 (iOS 3 was too old to build, and has been for some time). It could probably go back to iOS 4 but I don't have a device to test for that. Should [be](https://mixpanel.com/trends/#report/ios_7) [a](http://david-smith.org/iosversionstats/) [non issue](http://stats.unity3d.com/mobile/index-ios.html)