Bump version of bazel to 0.23 on master branch

Change-Id: I5f68acd75b473ea15443032648a6b3cad851a47e
diff --git a/jjb/onos/install-bazel.sh b/jjb/onos/install-bazel.sh
index f094cff..0afbcd8 100644
--- a/jjb/onos/install-bazel.sh
+++ b/jjb/onos/install-bazel.sh
@@ -3,7 +3,12 @@
 # exit on errors
 set -eu -o pipefail
 
-BAZEL_VERSION="0.19.2"
+if [ ${GERRIT_BRANCH} == "master" ]
+then
+    BAZEL_VERSION="0.23.0"
+else
+    BAZEL_VERSION="0.19.2"
+fi
 
 if [ ${BAZEL_VERSION} != "none" ]
 then