VOL-5159 - Create a beta release branch for openolt

.gitreview
----------
  o Assign defaultbranch=master for a visual distinction with release branch.

VERSION
-------
  o Bump version string to the next major dev version to avoid conflicts
    with the release branch.

Change-Id: I50084d1424ae8be1057394a68d6d47ff20bc8bce
diff --git a/.gitreview b/.gitreview
index 84dc7a2..e1a75fe 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,3 +3,4 @@
 port=29418
 project=openolt.git
 defaultremote=origin
+defaultbranch=master
\ No newline at end of file
diff --git a/VERSION b/VERSION
index a5c4c76..2eb846a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.9.0
+3.10.0-dev