[VOL-4290] Voltha go library updates for gRPC migration

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/google.golang.org/protobuf/AUTHORS b/vendor/google.golang.org/protobuf/AUTHORS
new file mode 100644
index 0000000..2b00ddb
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/AUTHORS
@@ -0,0 +1,3 @@
+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at https://tip.golang.org/AUTHORS.