title: Create alias for filtering ChoiceField in django-filters
body: <p>I have following filterset for some model:</p>
  
  <pre class="lang-py prettyprint-override"><code>class MyModel(models.Model):
      STATUS_ACTIVE = 0
      STATUS_DONE = 1
      STATUSES = (
          (STATUS_ACTIVE, 'Active'),
          (STATUS_DONE, 'Done'),
      )
  
      status = models.IntegerField(choices=STATUSES, default=STATUS_ACTIVE)
  
  
  class ModelFilter(FilterSet):
      status = ChoiceFilter(choices=MyModel.STATUSES)
  
      class Meta:
          model = MyModel
          fields = (
              'status',
          )
  </code></pre>
  
  <p>When I make request to some API, i should use status as number - <code>/app/model?status=0</code>.</p>
  
  <p>How to make alias for it, so that i can use <code>/app/model?status=active</code> instead of number, without changing model?</p>