support async replication #394

Job	Run time
Build images	6s
test (GODOG_FEATURE=active_nodes.feature make test)	7m 6s
test (GODOG_FEATURE=async.feature make test)	3m 29s
test (GODOG_FEATURE=cascade_replicas.feature make test)	7m 7s
test (GODOG_FEATURE=CLI.feature make test)	4m 3s
test (GODOG_FEATURE=crash_recovery.feature make test)	4m 22s
test (GODOG_FEATURE=events_reenable.feature make test)	2m 6s
test (GODOG_FEATURE=failover.feature make test)	12m 16s
test (GODOG_FEATURE=free_space.feature make test)	5m 53s
test (GODOG_FEATURE=host_discovery.feature make test)	3m 17s
test (GODOG_FEATURE=host_management.feature make test)	3m 1s
test (GODOG_FEATURE=maintenance.feature make test)	4m 44s
test (GODOG_FEATURE=offline_mode.feature make test)	2m 14s
test (GODOG_FEATURE=priority.feature make test)	5m 33s
test (GODOG_FEATURE=readonly_filesystem.feature make test)	1m 56s
test (GODOG_FEATURE=recovery.feature make test)	2m 48s
test (GODOG_FEATURE=repair.feature make test)	9m 47s
test (GODOG_FEATURE=statefile.feature make test)	4m 1s
test (GODOG_FEATURE=switchover_from.feature make test)	10m 25s
test (GODOG_FEATURE=switchover_to.feature make test)	10m 49s
test (GODOG_FEATURE=zk_failure.feature make test)	6m 59s
test (GODOG_FEATURE=zk_maintenance.feature make test)	4m 1s
	1h 56m 3s

Provide feedback