Improving stw and adding ability to clean-up mininet properly between runs.

Change-Id: Idb163bfa0cfd13b0ed7b9e4715ca7a2c0ffe69f6
diff --git a/tools/test/bin/onos-mininet b/tools/test/bin/onos-mininet
index ef2c8ea..4ce341e 100755
--- a/tools/test/bin/onos-mininet
+++ b/tools/test/bin/onos-mininet
@@ -66,4 +66,8 @@
         $mininet -X "stuff \"^C\\n\"" 2>/dev/null && \
         $mininet -X "stuff \"exit\\n\"" 2>/dev/null
     ;;
+cleanup)
+    ssh -t -t $remote sudo mn -c
+    ssh -t -t $remote "ps -ef | grep 'tail -n1 screenlog.0' | grep -v grep | cut -c10-15 | xargs kill -9"
+    ;;
 esac