Expose db.get_vlan_id_by_tag and db.get_vlan_tag_by_id()

Change-Id: I3b48a4bbd33fe46dfebae9994ca1a1035edf7a3c
diff --git a/util.py b/util.py
index 1e246fc..42a8bc0 100644
--- a/util.py
+++ b/util.py
@@ -67,6 +67,8 @@
                 ret = db.get_ports_by_base_vlan(data['vlan_id'])
             elif command == 'db.get_vlan_by_id':
                 ret = db.get_vlan_by_id(data['vlan_id'])
+            elif command == 'db.get_vlan_tag_by_id':
+                ret = db.get_vlan_tag_by_id(data['vlan_id'])
             elif command == 'db.get_vlan_id_by_name':
                 ret = db.get_vlan_id_by_name(data['name'])
             elif command == 'db.get_vlan_id_by_tag':