iOS 7 Support

I made a first step towards iOS 7 support. It does not work in all cases yet, but does under the following criteria:

1. UIViewControllerBasedStatusBarAppearance is set to NO in the info.plist
2. The view controller that the message should be displayed above has "Under Top Bars" deselected.
3. Prefered statusbar style is not UIStatusBarStyleLightContent