title: JSON serialization error in Django Rest Framework when using pagination
body: <p>I just tried to add pagination using <code>pagination_class = TenItemsSetPagination</code> to my class-based-view.
  As a result, I get an error trying to access my endpoint: <code>&lt;Response status_code=200, "text/html; charset=utf-8"&gt; is not JSON serializable</code></p>
  
  <p>views.py:</p>
  
  <pre><code>class AllCartsView(ListModelMixin, generics.GenericAPIView):
      permission_classes = [AllowAny]
      authentication_classes = []
      queryset = Cart.objects.all()
  
      serializer_class = carts_serializers.DataCartSerializer
      renderer_classes = (BrowsableAPIRenderer, JSONRenderer,)
      pagination_class = TenItemsSetPagination
  
      def get(self, request, *args, **kwargs):
          return self.list(request, *args, **kwargs)
  </code></pre>
  
  <p>paginators.py</p>
  
  <pre><code>class TenItemsSetPagination(PageNumberPagination):
      page_size = 10
  </code></pre>
  
  <ul>
  <li>Versions : Django 1.9.9 / DRF 3.3</li>
  </ul>
  
  <p>Any idea? Thanks.</p>