VOL-5115 - Create release branch voltha-2.12-beta

VERISON
-------
  o Bump version string to avoid conflicts with patch version.
  o Suffix *-dev on version string.

Change-Id: I83f25febf9dc5e31f44d6026b5ae15ff1459a094
diff --git a/VERSION b/VERSION
index 47b322c..186982e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.4.1
+3.4.2-dev