VOL-2154 : Moving back db/model to voltha-go

- Kept backend.go to limit impact in other components

Amendments:

- Removed db/model unit tests
- Forgot to fix some stash merges
- Removed unused "lock" parameter from kv clients
- Changed version for release

Change-Id: I25a03eb335ce22d49412be4bf2cceaff387dc4ae
diff --git a/VERSION b/VERSION
index f805d9f..0d3ad67 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.2.10-dev
+2.2.10