Required changes to support OF1.4, 1.5.

- OVS with OF1.4 passed `stc smoke` test
- OVS with OF1.5 still has issue
  As of OVS 2.5.0, OF1.5 mode responds with ill-formed of_meter_features_stats_reply
  org.projectfloodlight.openflow.exceptions.OFParseError: Wrong length: Expected=40(40), got=32
    at org.projectfloodlight.openflow.protocol.ver15.OFMeterFeaturesStatsReplyVer15$Reader.readFrom(OFMeterFeaturesStatsReplyVer15.java:281)

Change-Id: Ib78b9d92ecfb4bb667e24c4ee95bcd09aec160a6
diff --git a/tools/test/topos/default.py b/tools/test/topos/default.py
index 16e8788..b58b780 100644
--- a/tools/test/topos/default.py
+++ b/tools/test/topos/default.py
@@ -7,6 +7,11 @@
 class AttMplsTopo( Topo ):
     "Internet Topology Zoo Specimen."
 
+    def addSwitch( self, name, **opts ):
+        kwargs = { 'protocols' : 'OpenFlow13' }
+        kwargs.update( opts )
+        return super(AttMplsTopo, self).addSwitch( name, **kwargs )
+
     def __init__( self ):
         "Create a topology."