Category data format

The proposed data format is a result of:

• catalogCategoryListV1GetListGet

    {
        "_index": "storefront_catalog",
        "_type": "category",
        "_id": "22",
        "_score": 1,
        "_source": {
          "id": 22,
          "parent_id": 20,
          "name": "Bottoms",
          "is_active": true,
          "position": 2,
          "level": 3,
          "product_count": 0,
          "children_data": [
            {
              "is_active": true,
              "level": 4,
              "parent_id": 22,
              "product_count": 91,
              "name": "Pants",
              "id": 27,
              "position": 1,
              "children_data": []
            },
            {
              "is_active": true,
              "level": 4,
              "parent_id": 22,
              "product_count": 137,
              "name": "Shorts",
              "id": 28,
              "position": 2,
              "children_data": []
            }
          ],
          "tsk": 1509551138285
        }
      }