3692: Fixed test, and fixed the actual bug
Websocket server side fix, perform database notify in after_save callback on
the log object instead of in log_change on ArvadosBase because crunch-dispatch
was creating Log objects directly and bypassing the notification in log_change.
3692: Explicitly incorporate sequence number test into where clause
3692: Bug fix for inadequate grouping when constructing selection.
Merge branch '3692-event-bus-fix-and' closes #3692