title: DRF API return a list with filtered lists
body: <p>The data that is returned is one list with all fields. I want the data to be separated in different lists inside the main list. For example a list of data that is filtered on the date before today and a list after the date of today. I could write two endpoints and have the data filtered in the queryset, but that would take two separate API calls.</p>
  
  <p>The viewset:</p>
  
  <pre><code>class StudyPageViewSet(viewsets.ModelViewSet):
      """
      Study create, read, update, delete over API.
      """
      model = Study
      serializer_class = StudyPageSerializer
      permission_classes = (IsAuthenticated, IsAuthorPermission,)
  
      def get_queryset(self):
          return Study.on_site.all()
  </code></pre>
  
  <p>The Serializer:</p>
  
  <pre><code>class StudyPageSerializer(serializers.ModelSerializer):
  
      class Meta:
          model = Study
          fields = ('id', 'title', 'date', 'location')
          read_only_fields = ('id',)
  </code></pre>
  
  <p>Outcome should be like:</p>
  
  <pre><code>[ 
     { 
        "list_before_today":[ 
           { 
              "id":"5001",
              "title":"None"
           },
           { 
              "id":"5002",
              "title":"Glazed"
           },
  
        ]
     },
     { 
        "list_after_today":[ 
           { 
              "id":"5003",
              "title":"None"
           },
           { 
              "id":"5004",
              "title":"Glazed"
           },
  
        ]
     },
  
  ]
  </code></pre>
  
  <p>Current output:</p>
  
  <pre><code>[
      {
          "id": 588,
          "title": "title",
          .. : ..
      },
      {
          "id": 590,
          "title": "title2",
          .. : ..
      },
  ]
  </code></pre>
  
  <p>ps. the dots represent the other fields.</p>