Move XEP-0092 to new system.

sleekxmpp/plugins/xep_0092/__init__.py

@@ -6,6 +6,15 @@
     See the file LICENSE for copying permission.
 """
 
+from sleekxmpp.plugins.base import register_plugin
+
 from sleekxmpp.plugins.xep_0092 import stanza
 from sleekxmpp.plugins.xep_0092.stanza import Version
-from sleekxmpp.plugins.xep_0092.version import xep_0092
+from sleekxmpp.plugins.xep_0092.version import XEP_0092
+
+
+register_plugin(XEP_0092)
+
+
+# Retain some backwards compatibility
+xep_0092 = XEP_0092