Added ability to kill ONOS process after waiting for it to peacefully stop.

Change-Id: I5e768909622f7167e108929706471c054b245400
diff --git a/tools/test/bin/onos-wait-for-stop b/tools/test/bin/onos-wait-for-stop
index ebb1d6d..a497422 100755
--- a/tools/test/bin/onos-wait-for-stop
+++ b/tools/test/bin/onos-wait-for-stop
@@ -19,3 +19,8 @@
     done
     exit 1
 "
+
+[ $? -eq 0 ] && exit 0
+[ "$2" = "--kill" ] && onos-kill $node && exit 0
+
+exit 1