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

Change-Id: Idb163bfa0cfd13b0ed7b9e4715ca7a2c0ffe69f6
diff --git a/tools/test/scenarios/net-teardown.xml b/tools/test/scenarios/net-teardown.xml
index e9a17ef..829e917 100644
--- a/tools/test/scenarios/net-teardown.xml
+++ b/tools/test/scenarios/net-teardown.xml
@@ -16,6 +16,7 @@
 <scenario name="net-setup" description="Network teardown steps">
     <group name="Net-Teardown">
         <step name="Stop-Mininet" exec="onos-mininet stop"/>
+        <step name="Cleanup-Mininet" exec="onos-mininet cleanup" requires="~Stop-Mininet"/>
         <XXXstep name="Wipe-Out-Data-After" requires="~Stop-Mininet" exec="onos-wipe-out"/>
     </group>
 </scenario>
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