Adding serial_number information to OLTDevice

Change-Id: Ied682803092f0538cf5beaf59dcaeedd65be14c5
diff --git a/VERSION b/VERSION
index ac2cdeb..1ef72cb 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.1.3
+2.1.4-dev