Bumping VERSION to 2.6.0-dev

Change-Id: I5dc6a8291ee4af6aaf729f1fce648e9ea5708bee
diff --git a/VERSION b/VERSION
index aedc15b..8f87ff7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.5.3
+2.6.0-dev