title: Expand only "one" cell at a time? Currently I can open multiple up
body: <p>I followed Simon Lee's <a href="http://locassa.com/index.php/animate-uitableview-cell-height-change/" rel="nofollow">tutorial</a> on animating uitableview height change, and it's working amazing! The only problem I seem to be facing is that I can tap several cells, and they all will remain expanded regardless if another is already expanded. I only want one expanded at any given time, and if another is already expanded, for it to be closed before a new one expands. </p>
  
  <p>Simon mentioned that we should "store a single NSIndexPath as the current selected item instead on an array of indexes." I'm not exactly sure how to do this. If anyone could help out that would be awesome!</p>