Bump up the version after release

Change-Id: I6343eacd70cebef1b7747c68e23ff00d34e3cb15
diff --git a/VERSION b/VERSION
index 7ec1d6d..7c7e096 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.1.0
+2.1.1-dev