title: jquery nestable does not update
body: <p>I'm using jquery nestable to create a list of academic programs a prospective student might be interested in. 16 programs pulled from mysql and listed like this:</p>
  
  <pre><code>&lt;ol class="dd-list"&gt;
  
  if(mysqli_num_rows($result)) {
      $order = array();
      while($item = mysqli_fetch_assoc($result)) {
          echo '&lt;li class="dd-item" data-id="'.$item['id'].'"&gt;&lt;div class="dd-handle"&gt;',$item['program'],'&lt;/div&gt;&lt;/li&gt;';
      }
  
     &lt;/ol&gt;
   } else { 
     &lt;p&gt;Sorry!  There are no items in the system.&lt;/p&gt;
   }
  </code></pre>
  
  <p>No issue there. I have a second container to place the programs in:</p>
  
  <pre><code>&lt;div class="dd" id="nestable2"&gt;
   &lt;h4&gt;Place programs below in order of preference&lt;/h4&gt;
    &lt;ol class="dd-list dd-placeholder"&gt;
     &lt;li class="dd-item" data-id="17"&gt;
     &lt;div class="dd-handle"&gt;Health Sciences Advisor&lt;/div&gt;
    &lt;/li&gt;
   &lt;/ol&gt; 
  &lt;/div&gt;
  </code></pre>
  
  <p>And the original list and the output to the second container are output as serialized json data in textareas like this:</p>
  
  <pre><code> Serialised Output (per list)
   &lt;textarea id="nestable-output"&gt;&lt;/textarea&gt;
   &lt;textarea id="nestable2-output" name="nestable2-output"&gt;&lt;/textarea&gt;
  </code></pre>
  
  <p>Again no real issue. The textareas will be changed to hidden inputs later.Except that sometimes when i drag a list item from the left column to the right the value doesn't update. here is a link to the <a href="https://github.com/dbushell/Nestable/blob/master/jquery.nestable.js" rel="nofollow">jquery.nestable.js</a></p>
  
  <p>and here is the script in the form:</p>
  
  <pre><code>$(document).ready(function()
  {
  var updateOutput = function(e)
  {
      var list   = e.length ? e : $(e.target),
          output = list.data('output');
      if (window.JSON) {
          output.val(window.JSON.stringify(list.nestable('serialize')));//, null, 2));
      } else {
          output.val('JSON browser support required for this application.');
      }
  };
  // activate Nestable for list 1
  $('#nestable').nestable({
      group: 1
  })
  .on('change', updateOutput);
  // activate Nestable for list 2
  $('#nestable2').nestable({
      group: 1
  })
  .on('change', updateOutput);
  // output initial serialised data
  $('#nestable2').attr('data-id', 'newvalue');
  $('#nestable2').data('id', 'newvalue');
  
  updateOutput($('#nestable').data('output', $('#nestable-output')));
  
  updateOutput($('#nestable2').data('output', $('#nestable2-output')));
  
  });
  </code></pre>
  
  <p>It only fails sometimes. then if i re-order the list in the second container it updates, but won't update any new items until i re-order again. Any help is greatly appreciated.</p>