doc: specify listening addrs in the clustering example
*: lock the in using files; do not purge locked the wal files
*: do not backup files still in use
wal: rename openAtIndex -> open; OpenAtIndexUntilUsing -> openNotInUse
test: add fileutil to test
wal: fix wal doc
Merge pull request #1927 from xiang90/flock

*: lock the in using files; do not purge locked the wal files
sender: set strmSrv to nil after stoping it
Merge pull request #1943 from xiang90/fix_streamSrv

sender: set strmSrv to nil after stoping it
Merge pull request #1942 from xiang90/doc

doc: specify listening addrs in the clustering example
raft: use newRaft
Merge pull request #1945 from xiang90/raft_test

raft: use newRaft
Remove verbose logging and extraneous debug. Fixes #1904
Merge pull request #1946 from barakmich/less_logging

Remove verbose logging and extraneous debug. Fixes #1904
etcdserver: fix leader stats
etcdserver: update stats when become leader
Merge pull request #1948 from xiang90/stats

etcdserver: fix leader stats
etcdserver: add id tracker