Add default username to cleanup script

Change-Id: I58759bb2fb06a13c31e87f59fa1b15473dfe01f5
diff --git a/TestON/bin/cleanup.sh b/TestON/bin/cleanup.sh
index 3876cea..b6a937b 100755
--- a/TestON/bin/cleanup.sh
+++ b/TestON/bin/cleanup.sh
@@ -30,10 +30,11 @@
 sudo kill -9 `ps -ef | grep "ssh -X" | grep -v grep | awk '{print $2}'`
 sudo kill -9 `ps ax | grep '[p]ython -m SimpleHTTPServer 8000' | awk '{print $1}'`
 
+export user=${ONOS_USER:-$USER}
 if [[ -z "${OCN}" ]]; then
     echo "Mininet cleanup skipped because OCN is not defined"
 else
-    ssh $ONOS_USER@$OCN """
+    ssh $user@$OCN """
     sudo killall -9 dhclient dhcpd zebra bgpd vrrpd bird
     sudo mn -c
     sudo pkill -f mn.pid