Remove every old-style class.

src/plugins/plugin_xep_0054.py

@@ -64,7 +64,7 @@ PLUGIN_INFO = {
 "description": _("""Implementation of vcard-temp""")
 }
 
-class XEP_0054():
+class XEP_0054(object):
     #TODO: - check that nickname is ok
     #      - refactor the code/better use of Wokkel
     #      - get missing values