Support Sorted Set with LEX commands

It's included to Redis 2.8.9 (New)
Please refer https://groups.google.com/d/msg/redis-db/32VPw9X46Sg/GxHLzKeqRc0J for more details on Redis 2.8.9 and new commands.
(PF* commands are also explained)

* new commands : ZLEXCOUNT, ZRANGEBYLEX, ZREMRANGEBYLEX
  * added commands to Jedis, ShardedJedis, JedisCluster, PipelineBase with Binary / Normal(String)
  * description links
    * http://redis.io/commands/zlexcount
    * http://redis.io/commands/zrangebylex
    * http://redis.io/commands/zremrangebylex
  * Unit test included

@xetorthio @marcosnils Please review and comment, and label it! Thanks!