Bumping VERSION to 2.6.0-dev

Change-Id: Ic10ed98421cf6a17b9ad8710e6790206838168f6
diff --git a/VERSION b/VERSION
index 437459c..8f87ff7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.5.0
+2.6.0-dev