title: bootstrap accordion : how to collapse all at a click
body: <p>is there any option to collapse all the accordion when click on open or any other heading ?</p>
  
  <p>for example click one the second heading all accordion should collapse. 
  is it possible ?</p>
  
  <p><strong>DEMO</strong>  <a href="http://plnkr.co/edit/OxbVII?p=preview" rel="nofollow">http://plnkr.co/edit/OxbVII?p=preview</a></p>