title: disable validation in back button in django form
body: <p>I have a form representing a quiz with some questions and a result that appears in the end in Django 1.10. I need t implement two other buttons next to the "Check" button, one of them is "Mark" and the other is "Back".
  When I click on "back", I m handling well its behavior in the view but a pop up appears saying "Please Select One Of these Options".
  I need to disable it since user should not select one of the radio buttons if going back to the previous question.</p>
  
  <pre><code>&lt;form action="" method="POST"&gt;
      {% csrf_token %}
      &lt;input type=hidden name="question_id" value="{{ question.id }}"&gt;
      &lt;ul class="list-group"&gt;
          {% for answer in form.answers %}
            &lt;li class="list-group-item" &gt;{{ answer }}&lt;/li&gt;
          {% endfor %}
      &lt;/ul&gt;
      &lt;div id="buttons"&gt;
          &lt;input type="submit" name="question_btn" value={% trans "Check" %}  class="btn btn-lg center-block btn-outline btn-success" required&gt;
          &lt;input type="submit" name="question_btn" value={% trans "Back" %}
              class="btn btn-lg center-block btn-outline btn-success" required&gt;
  </code></pre>
  
  <p>
                  
  
  </p>
  
  <p>Any idea?</p>