Add default branch to .gitreview file

Change-Id: I34b08e6090d8f2b8f1c85e646256f576cc7db20f
diff --git a/.gitreview b/.gitreview
index 22fa62c..915882d 100644
--- a/.gitreview
+++ b/.gitreview
@@ -2,3 +2,4 @@
 host=review.gerrithub.io
 port=29418
 project=Mirantis/tcp-qa.git
+defaultbranch=2018.11.0
\ No newline at end of file