Bump VERSION to 2.1.0-dev after cord-7.0 release

Change-Id: I446f9e7b4c84874e9355784edc22d78b4e4e27d6
diff --git a/VERSION b/VERSION
index 157e54f..c10edc3 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.0.6
+2.1.0-dev