title: Add flex-active class to li then remove when slider advances
body: <p>I found a similar question <a href="https://stackoverflow.com/questions/25143437/adding-flex-active-class-to-the-li-instead-of-a-img">Adding flex-active class to the li instead of a/img</a></p>
  
  <p>but this solution is not removing the flex-active class from the active li siblings. </p>
  
  <p>I'll post the code as well for referense</p>
  
  <pre><code>$('.flexslider').flexslider({
  animation: "slide",
  directionNav: false,
  controlNav: "thumbnails",
  start: function(){
   $('.flex-control-nav .flex-active').parent('li').addClass('flex-active').siblings().removeClass('flex‌​-active');
  },
  after: function(){
  $('.flex-control-nav .flex-active').parent('li').addClass('flex-active').siblings().removeClass('flex‌​-active');
  }
  });
  </code></pre>
  
  <p>any help would be great!</p>