[VOL-4069] Measure and read Rx optical power for an ONU

The Rx optical power is read on the interface where the ONU is attached to, and returned in dBm.

Change-Id: I82856c265543e8043aef913790334a6c9ac795b2
diff --git a/VERSION b/VERSION
index a95f288..b1cbc1f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.4
+4.1.5