Davies Liu: fix version of changelog
Davies Liu: no changelog is ok, reduce syslog of download sessions
Davies Liu: disable timed jobs if not in MasterMode
Davies Liu: use changelog API in mastercomm
Davies Liu: kill cs connections if not in master mode
Davies Liu: flush changelogs to metalogger before exit
Davies Liu: download metadata if replay changelog failed
Davies Liu: change name of changelog and metadata
Davies Liu: bugfix
Davies Liu: refuse all client commands except STATS
Davies Liu: do not check metalogger if not in master mode
Davies Liu: update sessions when replay changelog and becoming master
Davies Liu: refactor: lastlogversion -> currentlogversion
Davies Liu: send archived changelog to metalogger
Davies Liu: fix fs_ismastermode(), reload order is reversed as init
Davies Liu: fix archived changelog, drop '\n', skip empty file
Davies Liu: disable fsync() to speed up download metadata
Davies Liu: adjust order of mastercomm, replay changelog first.
Davies Liu: add tool mfsrun: failover for mfsmaster

based on zookeeper, need kazoo
Davies Liu: accept all incoming connections in one event loop