title: change select option in django via javascript
body: <p>I have the following issue :</p>
  
  <p><strong>1/ Using Django, I am generating a form containing a set of countries.</strong></p>
  
  <p><em>The form is as follows :</em></p>
  
  <pre><code>country=forms.CharField(max_length=20
                       , widget=forms.Select(choices=countries)
                       , label=_('Country'))
  </code></pre>
  
  <p><em>The generated html is as follows</em></p>
  
  <pre><code>&lt;div class="form-group"&gt;
     &lt;label class="col-lg-1" for="id_country"&gt; … &lt;/label&gt;
     &lt;div class="col-lg-1"&gt;
        &lt;select id="id_country" class="chzn-done" name="country" style="display: none;"&gt; … &lt;/select&gt;
        &lt;div id="id_country_chzn" class="chzn-container chzn-container-single" style="width: 291px;" title=""&gt; 
     &lt;/div&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p><strong>2- I'd like to update the select dynamically using javascript</strong></p>
  
  <p>The code to update the select is provided below. The option is correctly changed. However, the "id_country_chzn" is not changed. The consequence is that although the option is changed, the value displayed for the end user is not changed. Is there a special trigger required ?</p>
  
  <p>The javascript code to update the option in the select is provided below. Could someone help me if I am missing anything ?</p>
  
  <pre><code>town.val('14').trigger('change');
  </code></pre>
  
  <p>Thanks a lot for your help</p>