Follow up changes on "pubsub numsub" output

* String, String to String, Long
* We're avoiding to break backward compatibility
** convert Long to String so that return type is same to old type
Support CLUSTER SLOTS command

* CLUSTER SLOTS returns a Redis-formatted mapping from slot ranges to IP/Port pairs serving that slot range
* description link including output format
** https://github.com/antirez/redis/commit/e14829de3025ffb0d3294e5e5a1553afd9f10b60
* Unit test included
Completing interface
Implements #701, add close() to JedisCluster
Changed weights from ints to doubles
Adopted test to use decimal weight values
Restored old method for int weights for backwards compatibility
Closes #656. Add a getNumActive() method to JedisPool to provide access to the current state of the internal pool.
Closes #656. Added 2 more asserts to ensure the count decrements correctly.