Bump to next minor version (3.4.0) post voltha-2.7 release

Change-Id: I6bf34b95433f2a6fa007882ebb95ba1ab365fff6
diff --git a/VERSION b/VERSION
index 619b537..1809198 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.3.3
+3.4.0