[GREEN] Implement include_positive query param for InvestigationCase list

apps/cases/views.py

@@ -68,6 +68,9 @@ class InvestigationCaseViewSet(viewsets.ModelViewSet):
 
     def get_queryset(self):
         if self.action == 'list':
+            query_include_positive = self.request.query_params.get('include_positive', None)
+            if query_include_positive is not None:
+                return self.queryset
             return self.queryset.filter(Q(outcome__isnull=True) | Q(outcome__icontains="-"))
         return self.queryset