CORD-2772 set version number for vtn service

Change-Id: I8374fa9e7aeb03d5e0b769248a5e007c5921c8b2
diff --git a/VERSION b/VERSION
new file mode 100644
index 0000000..519af9a
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+6.0.0.dev