title: Setting the "title" of a UIPopoverController?
body: <p>I'm sure there's something obvious I'm missing here, but I know that popover controls can have "titles", a header area that has a line of text above the content view (e.g. the "Tools"  popover in iWork). </p>
  
  <p>How can I add this in my own popovers?</p>
  
  <p>Thanks.</p>