bumping to version 2.7

Change-Id: I27d5322793806aca222902bd6f876404b4bb49a2
diff --git a/.gitreview b/.gitreview
index 328aec6..fa31103 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,4 +3,4 @@
 port=29418
 project=onos.git
 defaultremote=origin
-defaultbranch=master
+defaultbranch=onos-2.7