use the singleton logger object

There was no need for each test file to have its own logger.
diff --git a/tests/port_stats.py b/tests/port_stats.py
index 96d3cc5..5cfb1bb 100644
--- a/tests/port_stats.py
+++ b/tests/port_stats.py
@@ -23,8 +23,6 @@
 #@var fs_port_map Local copy of the configuration map from OF port
 # numbers to OS interfaces
 fs_port_map = None
-#@var fs_logger Local logger object
-fs_logger = None
 #@var fs_config Local copy of global configuration data
 fs_config = None
 
@@ -54,17 +52,14 @@
     basic.test_set_init(config)
 
     global fs_port_map
-    global fs_logger
     global fs_config
 
-    fs_logger = logging.getLogger("flow_stats")
-    fs_logger.info("Initializing test set")
     fs_port_map = config["port_map"]
     fs_config = config
 
 def sendPacket(obj, pkt, ingress_port, egress_port, test_timeout):
 
-    fs_logger.info("Sending packet to dp port " + str(ingress_port) +
+    logging.info("Sending packet to dp port " + str(ingress_port) +
                    ", expecting output on " + str(egress_port))
     obj.dataplane.send(ingress_port, str(pkt))
 
@@ -78,7 +73,7 @@
                                                        exp_pkt=exp_pkt_arg)
     obj.assertTrue(rcv_pkt is not None,
                    "Packet not received on port " + str(egress_port))
-    fs_logger.debug("Packet len " + str(len(rcv_pkt)) + " in on " + 
+    logging.debug("Packet len " + str(len(rcv_pkt)) + " in on " + 
                     str(rcv_port))
     obj.assertEqual(rcv_port, egress_port,
                     "Packet received on port " + str(rcv_port) +
@@ -90,17 +85,17 @@
     stat_req = message.port_stats_request()
     stat_req.port_no = port
 
-    fs_logger.info("Sending stats request")
+    logging.info("Sending stats request")
     response, pkt = obj.controller.transact(stat_req, timeout=2)
     obj.assertTrue(response is not None, 
                     "No response to stats request")
     obj.assertTrue(len(response.stats) == 1,
                     "Did not receive port stats reply")
     for item in response.stats:
-        fs_logger.info("Sent " + str(item.tx_packets) + " packets")
+        logging.info("Sent " + str(item.tx_packets) + " packets")
         packet_sent = item.tx_packets
         packet_recv = item.rx_packets
-    fs_logger.info("Port %d stats count: tx %d rx %d" % (port, packet_sent, packet_recv))
+    logging.info("Port %d stats count: tx %d rx %d" % (port, packet_sent, packet_recv))
     return packet_sent, packet_recv
 
 def verifyStats(obj, port, test_timeout, packet_sent, packet_recv):
@@ -111,7 +106,7 @@
     all_packets_sent = 0
     sent = recv = 0
     for i in range(0,test_timeout):
-        fs_logger.info("Sending stats request")
+        logging.info("Sending stats request")
         response, pkt = obj.controller.transact(stat_req,
                                                 timeout=test_timeout)
         obj.assertTrue(response is not None, 
@@ -121,10 +116,10 @@
         for item in response.stats:
             sent = item.tx_packets
             recv = item.rx_packets
-            fs_logger.info("Sent " + str(item.tx_packets) + " packets")
+            logging.info("Sent " + str(item.tx_packets) + " packets")
             if item.tx_packets == packet_sent:
                 all_packets_sent = 1
-            fs_logger.info("Received " + str(item.rx_packets) + " packets")
+            logging.info("Received " + str(item.rx_packets) + " packets")
             if item.rx_packets == packet_recv:
                 all_packets_received = 1
 
@@ -132,8 +127,8 @@
             break
         sleep(1)
 
-    fs_logger.info("Expected port %d stats count: tx %d rx %d" % (port, packet_sent, packet_recv))
-    fs_logger.info("Actual port %d stats count: tx %d rx %d" % (port, sent, recv))
+    logging.info("Expected port %d stats count: tx %d rx %d" % (port, packet_sent, packet_recv))
+    logging.info("Actual port %d stats count: tx %d rx %d" % (port, sent, recv))
     obj.assertTrue(all_packets_sent,
                    "Packet sent does not match number sent")
     obj.assertTrue(all_packets_received,
@@ -160,7 +155,7 @@
         of_ports.sort()
         self.assertTrue(len(of_ports) > 1, "Not enough ports for test")
 
-        rc = delete_all_flows(self.controller, fs_logger)
+        rc = delete_all_flows(self.controller)
         self.assertEqual(rc, 0, "Failed to delete all flows")
 
         # build packet
@@ -174,7 +169,7 @@
         # build flow
         ingress_port = of_ports[0];
         egress_port = of_ports[1];
-        fs_logger.info("Ingress " + str(ingress_port) + 
+        logging.info("Ingress " + str(ingress_port) + 
                        " to egress " + str(egress_port))
         match.in_port = ingress_port
         flow_mod_msg = message.flow_mod()
@@ -187,7 +182,7 @@
         self.assertTrue(flow_mod_msg.actions.add(act), "Could not add action")
        
         # send flow
-        fs_logger.info("Inserting flow")
+        logging.info("Inserting flow")
         rv = self.controller.message_send(flow_mod_msg)
         self.assertTrue(rv != -1, "Error installing flow mod")
         self.assertEqual(do_barrier(self.controller), 0, "Barrier failed")
@@ -198,7 +193,7 @@
 
         # send packet N times
         num_sends = random.randint(10,20)
-        fs_logger.info("Sending " + str(num_sends) + " test packets")
+        logging.info("Sending " + str(num_sends) + " test packets")
         for i in range(0,num_sends):
             sendPacket(self, pkt, ingress_port, egress_port,
                        test_timeout)
@@ -234,7 +229,7 @@
         act.port = egress_port
         self.assertTrue(flow_mod_msg.actions.add(act), "Could not add action")
 
-        fs_logger.info("Ingress " + str(ingress_port) + 
+        logging.info("Ingress " + str(ingress_port) + 
                        " to egress " + str(egress_port))
 
         return flow_mod_msg
@@ -252,7 +247,7 @@
         egress_port1 = of_ports[1];
         egress_port2 = of_ports[2];
 
-        rc = delete_all_flows(self.controller, fs_logger)
+        rc = delete_all_flows(self.controller)
         self.assertEqual(rc, 0, "Failed to delete all flows")
 
         pkt1 = simple_tcp_packet()
@@ -261,10 +256,10 @@
         pkt2 = simple_tcp_packet(dl_src='0:7:7:7:7:7')
         flow_mod_msg2 = self.buildFlowModMsg(pkt2, ingress_port, egress_port2)
        
-        fs_logger.info("Inserting flow1")
+        logging.info("Inserting flow1")
         rv = self.controller.message_send(flow_mod_msg1)
         self.assertTrue(rv != -1, "Error installing flow mod")
-        fs_logger.info("Inserting flow2")
+        logging.info("Inserting flow2")
         rv = self.controller.message_send(flow_mod_msg2)
         self.assertTrue(rv != -1, "Error installing flow mod")
         self.assertEqual(do_barrier(self.controller), 0, "Barrier failed")
@@ -275,9 +270,9 @@
         initTxOutPort2, initRxOutPort2 = getStats(self, egress_port2)
 
         num_pkt1s = random.randint(10,30)
-        fs_logger.info("Sending " + str(num_pkt1s) + " pkt1s")
+        logging.info("Sending " + str(num_pkt1s) + " pkt1s")
         num_pkt2s = random.randint(10,30)
-        fs_logger.info("Sending " + str(num_pkt2s) + " pkt2s")
+        logging.info("Sending " + str(num_pkt2s) + " pkt2s")
         for i in range(0,num_pkt1s):
             sendPacket(self, pkt1, ingress_port, egress_port1, test_timeout)
         for i in range(0,num_pkt2s):