bugfix: arrays use .append() instead of .add()

inconsistent Python API ftw!

ffstatus/basestorage.py

@@ -94,7 +94,7 @@ class BaseStorage(object):
             sum_clients += node.get('clientcount', 0)
             nodemacs = [x for x in node.get('macs', [])]
             if 'mac' in node:
-                nodemacs.add(node['mac'])
+                nodemacs.append(node['mac'])
             for client in node.get('clients', []):
                 if client in nodemacs:
                     continue