roc-umbrella: release 1.4.65 on aether-1.6

Change-Id: Ie2686f51906c021eef6364dcc90ddbb371b031b5
diff --git a/Makefile b/Makefile
index 8517d19..8930721 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,10 @@
         {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}; \
     '
 
-yang-lint:
+pyang:
+	pyang -v || pip install pyang
+
+yang-lint: pyang
 	#pyang --lint ./config-models/*.x/files/yang/*.yang
 	pyang --lint ./config-models/aether-1.x/files/yang/*.yang
 	pyang --lint ./config-models/aether-2.x/files/yang/*.yang