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
** e14829de30
* Unit test included

src/main/java/redis/clients/jedis/ClusterCommands.java

@@ -38,4 +38,6 @@ public interface ClusterCommands {
     List<String> clusterSlaves(final String nodeId);
     
     String clusterFailover();
+    
+    List<Object> clusterSlots();
 }