Bump up the version after release

Change-Id: If0baa1d0c09b772d853e088290ba173aab5e7c0b
diff --git a/VERSION b/VERSION
index 7ec1d6d..7c7e096 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.1.0
+2.1.1-dev