title: how to validate select2 multiple option in jquery
body: <p>select2 jquery, this is my output:</p>
  
  <pre><code>$('.select3_multi').select2({ placeholder: "Select Multiple", allowClear: true}).change(function(){
      $('.select3_multi').valid();
  });
  </code></pre>
  
  <p>html source:</p>
  
  <pre><code>&lt;select class="select3_multi form-control" multiple="multiple"  name="test[]" id="test"  tabindex="-1"style="width:335px!important" class="required"&gt;
      &lt;option value=""&gt;Select Test&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>