added feature : JedisPool / JedisSentinelPool resets returning object's state (watched, multi)

It's based on requests #500, and it seems to make sense.

* BinaryClient / BinaryJedis : added feature to reset its state (watched, multi)
* JedisPool / JedisSentinelPool : calls new feature (reset state) when Jedis object returns to pool

I used flag for check 'watched', but 'unwatch' command is no problem for non-watched status.
So, flag can be removed if we call 'unwatch' every call to reset state.