title: iOS7 view with autolayout to line up above TabBar
body: <p>I know I know.. Another iOS7 question.<br>
  I have a view in a UINavigationController which gets added to a TabBarController.
  In iOS6 I used the vertical constraint 'bottom space to super view, default' which would give me 10 pixels about the TabBar.<br>
  This same constraint doesn't appear to work in iOS 7. Is the TabBar not considered the superview anymore? Is there another constraint I should be using?</p>