VOL-1616 / VOL-1611 : Fix device state issue and memory discrepencies

- Applied mutex on node object to resolve in-memory data conflicts
- Introduced a refresh period for in-memory data

Amendments:

- Fixed node.go file format
- Bumped VERSION to 2.1.0-dev
- Use a RLock for GetLastUpdate

Change-Id: I57e88fe3ec5cceed0d4fcdb240ae9191b49ebe33
diff --git a/VERSION b/VERSION
index 227cea2..c10edc3 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.0.0
+2.1.0-dev