title: Django queryset __contains case sensitive?
body: <p>I want to perform a simple query:</p>
  
  <pre><code>Pizza.object.filter(topping__contains='PEPERONI')
  </code></pre>
  
  <p>Like this, it works like a charm. But if I try that:</p>
  
  <pre><code>Pizza.object.filter(topping__contains='peperoni')
  </code></pre>
  
  <p>It is not working. </p>
  
  <p>Do you know why it is case sensitive ? Is there an option to cancel this feature from django ?</p>