api/rest.py,core/models.py: WIP support for attachement access

WIP draft of support for accessing attachments.

squad/api/rest.py

@@ -1308,11 +1308,19 @@ class StatusViewSet(NestedViewSetMixin, ModelViewSet):
     ordering = ('id',)
 
 
-class AttachmentSerializer(serializers.ModelSerializer):
+class AttachmentSerializer(serializers.HyperlinkedModelSerializer):
 
     class Meta:
         model = Attachment
-        fields = ('filename', 'mimetype', 'length')
+        fields = '__all__'
+
+
+class AttachmentViewSet(NestedViewSetMixin, ModelViewSet):
+
+    queryset = Attachment.objects.all()
+    serializer_class = AttachmentSerializer
+    pagination_class = CursorPaginationWithPageSize
+    ordering = ('id',)
 
 
 class TestRunSerializer(DynamicFieldsModelSerializer, serializers.HyperlinkedModelSerializer):
@@ -1901,3 +1909,4 @@ class Meta:
 router.register(r'metricthresholds', MetricThresholdViewSet)
 router.register(r'reports', DelayedReportViewSet)
 router.register(r'statuses', StatusViewSet)
+router.register(r'attachments', AttachmentViewSet)