Bump xos libraries to version 4.0.0

Change-Id: Ic541ddeb6e87e1208875f28ff5e6c72c597f5ec0
diff --git a/VERSION b/VERSION
index 3ef5fad..d72f262 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.2.4-dev
+2.0.0-dev