Actually fixes #200 adds label_field => label_value to API

However ideally we only do this with a API version increment.

modules/radar/radar_services/plugins/services_entity/resource_controller.inc

@@ -177,6 +177,19 @@ class RadarServicesEntityResourceController extends ServicesEntityResourceContro
           // For referenced entities only return the URI.
           if ($id = $property->getIdentifier()) {
             $data[$name] = $this->get_resource_reference($property->type(), $id);
+            // So in common with some of our other errors the entity won't load
+            // here as it's a UUID. Replacing the entity controller would
+            // probably do it? For now fix the issue at hand.
+            $entity_info = entity_get_info($property->type());
+            $entities = entity_uuid_load($property->type(), [$id]);
+            $entity_label = empty($entity_info['entity keys']['label']) ? 'label' : $entity_info['entity keys']['label'];
+            if (!empty($entities)) {
+              $entity = reset($entities);
+              $data[$name][$entity_label] = entity_label($property->type(), $entity);
+            }
+            else {
+              $data[$name][$entity_label] = '';
+            }
           }
         }
         elseif ($property instanceof EntityValueWrapper) {