support async replication #496

Job	Run time
Build images	5s
test (GODOG_FEATURE=active_nodes.feature make test)	6m 52s
test (GODOG_FEATURE=async.feature make test)	3m 38s
test (GODOG_FEATURE=cascade_replicas.feature make test)	7m 6s
test (GODOG_FEATURE=CLI.feature make test)	3m 50s
test (GODOG_FEATURE=crash_recovery.feature make test)	4m 34s
test (GODOG_FEATURE=events_reenable.feature make test)	1m 48s
test (GODOG_FEATURE=failover.feature make test)	12m 13s
test (GODOG_FEATURE=free_space.feature make test)	5m 27s
test (GODOG_FEATURE=host_discovery.feature make test)	3m 1s
test (GODOG_FEATURE=host_management.feature make test)	3m 6s
test (GODOG_FEATURE=maintenance.feature make test)	4m 29s
test (GODOG_FEATURE=offline_mode.feature make test)	2m 18s
test (GODOG_FEATURE=priority.feature make test)	5m 20s
test (GODOG_FEATURE=readonly_filesystem.feature make test)	2m 14s
test (GODOG_FEATURE=recovery.feature make test)	2m 50s
test (GODOG_FEATURE=repair.feature make test)	9m 50s
test (GODOG_FEATURE=repl_mon.feature make test)	3m 27s
test (GODOG_FEATURE=statefile.feature make test)	4m 0s
test (GODOG_FEATURE=switchover_from.feature make test)	9m 31s
test (GODOG_FEATURE=switchover_to.feature make test)	10m 12s
test (GODOG_FEATURE=zk_failure.feature make test)	7m 3s
test (GODOG_FEATURE=zk_maintenance.feature make test)	4m 4s
	1h 56m 58s

Provide feedback