Make connection pool thread safe
Update README
Travis CI: add redis-server
README: add build status image
sleep longer time to wait for Redis server
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
tune for Travis CI
Merge pull request #2 from xiaogaozi/thread-safe

Make connection pool thread safe