Use service model for history

Rather than have the view layer interact directly with the API client.
This will let us add extra transformation in the model layer at some
point.

app/models/service.py

@@ -631,3 +631,7 @@ class Service(JSONModel):
         ):
             if test:
                 yield BASE + '_incomplete' + tag
+
+    @cached_property
+    def history(self):
+        return service_api_client.get_service_history(self.id)['data']