title: Serialise choice text for IntegerField with choices
body: <p>I'd like to serialise a model with a lot of choices like such:</p>
  
  <pre><code>class House(models.Model):
  ACCESSIBILITY_CHOICES = (
      (ACCESSIBILITY_FULL, 'Full'),
      (ACCESSIBILITY_PARTIAL, 'Partial'),
      (ACCESSIBILITY_NONE, 'None')
  )
  
  accessibility = models.IntegerField(max_length=1, choices=ACCESSIBILITY_CHOICES, null=True)
  </code></pre>
  
  <p>I love that the default serializer such as:</p>
  
  <pre><code>class HouseView(generics.ListCreateAPIView):
      model = House
      serializer_class = HouseSerializer
  
  class HouseSerializer(serializers.ModelSerializer):
  
      class Meta:
          model = House
  </code></pre>
  
  <p>works great if I want just the integer value</p>
  
  <pre><code>{accessibility:1}
  </code></pre>
  
  <p>However, what I'd like to get </p>
  
  <pre><code>{accessibility:'Full'}
  </code></pre>
  
  <p>Help is kindly appreciated. 
  Many thanks.</p>