feature: set up replication when instance joins
Picodata already assigns replicaset_id to an instance when it joins,
but it wasn't used in Tarantool box.cfg yet. Now it is.
It's also important to set up listen port in start_join immediately.
Without it Tarantool will stuck waiting for connection to self.
Part of #52 (closed)
Edited by Yaroslav Dynnikov