Add new methods to lookup ports by switch and port number

Change-Id: I3464f1fad1bd3d5c421dfa2db69ddce3b95f2603
diff --git a/util.py b/util.py
index 45f82a3..e1dc263 100644
--- a/util.py
+++ b/util.py
@@ -57,6 +57,8 @@
                 ret = db.get_ports_by_switch(data['switch_id'])
             elif command == 'db.get_port_by_switch_and_name':
                 ret = db.get_port_by_switch_and_name(data['switch_id'], data['name'])
+            elif command == 'db.get_port_by_switch_and_number':
+                ret = db.get_port_by_switch_and_number(data['switch_id'], int(data['number']))
             elif command == 'db.get_current_vlan_id_by_port':
                 ret = db.get_current_vlan_id_by_port(data['port_id'])
             elif command == 'db.get_base_vlan_id_by_port':