VOL-1460 Updated core to use voltha-protos instead of local protos
Moved protos to python directory in order to maintain functionaly of containers built there.
Added capability to do local builds of protos
Added instructions on running dep ensure for getting protos.
Updated github.com/golang/protobuf version to v1.3.1

Change-Id: Ia6ef55f07f0d5dcb5b750d7c37b21b71db85bfc4
diff --git a/vendor/google.golang.org/grpc/backoff.go b/vendor/google.golang.org/grpc/backoff.go
index fa31565..97c6e25 100644
--- a/vendor/google.golang.org/grpc/backoff.go
+++ b/vendor/google.golang.org/grpc/backoff.go
@@ -17,7 +17,7 @@
  */
 
 // See internal/backoff package for the backoff implementation. This file is
-// kept for the exported types and API backward compatility.
+// kept for the exported types and API backward compatibility.
 
 package grpc