用 CentOS7/RHEL7 架設 Redis Cluster Servers

參考文獻：

1. http://blog.csdn.net/dc_726/article/details/48552531
2. http://redis.io/topics/replication
3. https://www.digitalocean.com/community/tutorials/how-to-configure-a-redis-cluster-on-ubuntu-14-04
4. https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04