title: django QueryDict only returns the last value of a list
body: <p>Using django 1.8, I'm observing something strange.
  Here is my javascript:</p>
  
  <pre><code>function form_submit(){
    var form = $('#form1_id');
    request = $.post($(this).attr('action'), form.serialize(), function(response){
       if(response.indexOf('Success') &gt;= 0){
          alert(response);
       }
    },'text')
    .fail(function() {
      alert("Failed to save!");
    });
    return false;
  }
  </code></pre>
  
  <p>and here are the parameters displayed in views.py</p>
  
  <pre><code>print request.POST
  &lt;QueryDict: {u'form_4606-name': [u''], u'form_4606-parents': [u'4603', u'2231', u'2234']}&gt;
  </code></pre>
  
  <p>but I cannot extract the parents:</p>
  
  <pre><code>print request.POST['form_4606-parents']
  2234
  </code></pre>
  
  <p>Why is it just giving me the last value?
  I think there is something wrong with the serialization, but I just cannot figure out how to resolve this.</p>