- XMPP Events <=> AP Events conversion
- `Join`/`Leave` activities are converted to RSVP attachments and vice versa
- fix caching/notification on item published on a virtual pubsub node
- add Ad-Hoc command to convert XMPP Jid/Node to virtual AP Account
- handle `Update` activity
- on `convertAndPostItems`, `Update` activity is used instead of `Create` if a version of
the item is already present in cache
- `events` field is added to actor data (and to `endpoints`), it links the `outbox` of the
actor mapping the same JID with the Events node (i.e. it links to the Events node of the
entity)
- fix subscription to nodes which are not the microblog one
rel 372
