documentation: added aioetcd to client libs
documentation: fix min python version for aioetcd
Disable unused sudo-ability from Travis in hopes of faster startup
times.
Merge pull request #1929 from lisael/master

added aioetcd (python 3.4+) to client libs list
Merge pull request #1931 from barakmich/travis

Disable unused sudo-ability from Travis in hopes of faster startup
discovery: fix watch index
Merge pull request #1934 from xiang90/fix_test

discovery: fix watch index
pkg/transport: change write size from 1MB -> 5MB

As we move to container-based infrastructure testing env
on travis, the tcp write buffer is more than 1MB. Change
the test according to the change on the testing env.
Merge pull request #1936 from xiang90/fix_test

pkg/transport: change write size from 1MB -> 5MB
modify directory deletion sequence
Merge pull request #1926 from jainvipin/master

minor fix for #1786
rafthttp: better logging
raft: log term as %d
Merge pull request #1940 from xiang90/raft_log

rafT: log term as %d
Merge pull request #1939 from xiang90/sender_logging

rafthttp: better logging
etcdserver: protect the sender map in SendHub
Merge pull request #1938 from yichengq/262

etcdserver: protect the sender map in SendHub
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