title: Django Picklist Won't Take Decimal Value
body: <p>I am trying to get a simple django app to fill a form with a decimal field pick-list. The admin form displays it properly (selecting the right item from the list), but submitting gives an error:</p>
  
  <pre><code>'Select a valid choice. 1.046 is not one of the available choices.' 
  </code></pre>
  
  <p>My model looks like this:</p>
  
  <pre><code>    GRAVITY_CHOICES = (
      (1.041, '1.041'),
      (1.042, '1.042'),
      (1.043, '1.043'),
      (1.044, '1.044'),
      (1.045, '1.045'),
      (1.046, '1.046'),
      )
  ...
      OG = models.DecimalField(max_digits=4, decimal_places=3, choices=GRAVITY_CHOICES, null=True, blank=True)
  </code></pre>
  
  <p>It works perfectly fine when I submit a decimal value with the field as a simple text input field, but the pick list will make things easier.</p>
  
  <p>What am I missing?</p>