title: prevent UINavigatonBar from overlapping content
body: <p>The problem I have is only with iOS7. 
  I have a <code>UINavigationController</code> which includes a <code>UITableView</code>. The NavigationBar is on top of the table content. So far so good. As soon as I click on a cell I show a <code>UIViewController</code>. As it slides in the NavigationBar is overlapping the ViewControllers content and at the bottom of the view I have an empty space (size of NavBar).</p>
  
  <p>How can I get the same old behavior as of iOS6? I don't want the NavBar to be translucent in any way.</p>