Implement lookup_switch_by_name

Change-Id: I76cae8665431837b158a30bb26224963c59e448a
diff --git a/admin.py b/admin.py
index 52f6922..3806f49 100644
--- a/admin.py
+++ b/admin.py
@@ -302,6 +302,15 @@
         print 'Deleted vlan_id %d' % vlan_id
     except InputError as inst:
         print 'Failed: %s' % inst
+elif opts.lookup_switch_by_name is not None:
+    try:
+        switch_id = db.get_switch_id_by_name(opts.lookup_switch_by_name)
+        if switch_id is not None:
+            print 'Switch %s has switch_id %d' % (opts.lookup_switch_by_name, switch_id)
+        else:
+            print 'No switch found for name %s' % opts.lookup_switch_by_name
+    except InputError as inst:
+        print 'Failed: %s' % inst    
 else:
     print 'No recognised command given. Try -h for help'