SYN-258: get_recent_events_for_room only accepts stream tokens, convert the topological token to a stream token before passing it to get_recent_events_for_room

Federation fixes.

Pass through list of room hosts from room alias query to federation so that it can retry against different room hosts

SYN-202: Log as WARN the 404 'Presence information not visible' errors instead of as ERROR since they were spamming the logs

Apply sanity to the transport client interface. Convert 'make_join' and 'send_join' to accept iterables of destinations

Change context.auth_events to what the auth_events would be bases on context.current_state, rather than based on the auth_events from the event.

Rearrange persist_event so that do all the queries that need to be done before returning early if we have already persisted that event.

Keep around the old (buggy) version of the prune_event function so that we can use it to check signatures for events on old servers