[VOL-1505]  This update enables the core to add a key when
publishing an event onto kafka.   The corresponding update is
done in the adapter GO components.   Similar changes remain to
be done in pyvoltha.

Change-Id: I0bb1e3cb8c2fa9e0214f96d863819755d34a0bb9
diff --git a/db/kvstore/client.go b/db/kvstore/client.go
index a8e6311..34ab711 100644
--- a/db/kvstore/client.go
+++ b/db/kvstore/client.go
@@ -84,6 +84,8 @@
 	ReleaseAllReservations() error
 	RenewReservation(key string) error
 	Watch(key string) chan *Event
+	AcquireLock(lockName string, timeout int) error
+	ReleaseLock(lockName string) error
 	CloseWatch(key string, ch chan *Event)
 	Close()
 }