Publishes, retractions, purges, and deletions now raise the events:
- pubsub_publish
- pubsub_retract
- pubsub_purge
- pubsub_delete
In addition, custom events may be raised based on the node that
generated the notification. For example:
xmpp['xep_0060'].map_node_event('http://jabber.org/protocol/tune',
'user_tune')
will allow for using the events:
- user_tune_publish
- user_tune_retract
- user_tune_purge
- user_tune_delete