VOL-1387 : Added watch mechanism

- Fixed a few failure cases
- Adjusted a few logs

Change-Id: Ied1ecb3d8996a338eee00e9643685482700e860b
diff --git a/db/model/revision.go b/db/model/revision.go
index a848bbf..0a58ccd 100644
--- a/db/model/revision.go
+++ b/db/model/revision.go
@@ -25,6 +25,7 @@
 	SetHash(hash string)
 	GetHash() string
 	ClearHash()
+	SetupWatch(key string)
 	SetBranch(branch *Branch)
 	GetBranch() *Branch
 	Get(int) interface{}