[WIP] add failoverQuorum semisync check, refactor failoverQuorum (#115) #529

Job	Run time
Build images	1m 54s
test (GODOG_FEATURE=active_nodes.feature make test)	7m 9s
test (GODOG_FEATURE=async.feature make test)	3m 29s
test (GODOG_FEATURE=cascade_replicas.feature make test)	7m 3s
test (GODOG_FEATURE=CLI.feature make test)	4m 0s
test (GODOG_FEATURE=crash_recovery.feature make test)	5m 6s
test (GODOG_FEATURE=events_reenable.feature make test)	2m 48s
test (GODOG_FEATURE=failover.feature make test)	14m 14s
test (GODOG_FEATURE=free_space.feature make test)	5m 51s
test (GODOG_FEATURE=host_discovery.feature make test)	3m 11s
test (GODOG_FEATURE=host_management.feature make test)	3m 13s
test (GODOG_FEATURE=maintenance.feature make test)	4m 20s
test (GODOG_FEATURE=offline_mode.feature make test)	2m 7s
test (GODOG_FEATURE=priority.feature make test)	5m 54s
test (GODOG_FEATURE=readonly_filesystem.feature make test)	2m 15s
test (GODOG_FEATURE=recovery.feature make test)	3m 9s
test (GODOG_FEATURE=repair.feature make test)	10m 5s
test (GODOG_FEATURE=repl_mon.feature make test)	3m 17s
test (GODOG_FEATURE=statefile.feature make test)	3m 52s
test (GODOG_FEATURE=switchover_from.feature make test)	9m 42s
test (GODOG_FEATURE=switchover_to.feature make test)	10m 40s
test (GODOG_FEATURE=zk_failure.feature make test)	7m 16s
test (GODOG_FEATURE=zk_maintenance.feature make test)	4m 7s
	2h 4m 42s

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