title: Ng-nestable angular buttons for expand and collapse
body: <p>Can someone let me know how to create button for collapse all/expand all to jquery nestable but in angularjs version? 
  <a href="https://github.com/kamilkp/ng-nestable" rel="nofollow">https://github.com/kamilkp/ng-nestable</a></p>
  
  <p>I'm able to do it when it start: $nestable.collapseAllOnStart = false; but i also want to have two buttons to collapse all/expand all.</p>
  
  <p>Is it even possible? 
  Edit: For now i'm using jquery way:</p>
  
  <pre><code>&lt;menu id="nestable-menu"&gt;
      &lt;button type="button" class="btn btn-wide btn-o btn-info" data-action="expand-all" translate="licences.expandAll"&gt;Expand All&lt;/button&gt;
      &lt;button type="button" class="btn btn-wide btn-o btn-warning" data-action="collapse-all" translate="licences.collapseAll"&gt;Collapse All&lt;/button&gt;
  &lt;/menu&gt;
  &lt;div class="row"&gt;
      &lt;div class="col-md-12"&gt;
          &lt;div ng-nestable ng-model="departmentsTest" clas="dd"&gt;
              {{$item.text}}
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And script in html page:</p>
  
  <pre><code>&lt;script&gt;
  $('#nestable-menu').on('click', function(e)
      {
          var target = $(e.target),
              action = target.data('action');
          if (action === 'expand-all') {
              $('.dd').nestable('expandAll');
          }
          if (action === 'collapse-all') {
              $('.dd').nestable('collapseAll');
          }
      });
  </code></pre>
  
  <p>But to be honest i would like to use angular for this.</p>