Cluster: include node IDs in SLOTS output.
Cluster: include node IDs in SLOTS output.

CLUSTER SLOTS now includes IDs in the nodes description associated with
a given slot range. Certain client libraries implementations need a way
to reference a node in an unique way, so they were relying on CLUSTER
NODES, that is not a stable API and may change frequently depending on
Redis Cluster future requirements.

louisliangjun/redis,splitice/redis,louisliangjun/redis,louisliangjun/redis,splitice/redis,louisliangjun/redis,splitice/redis,ramonsnir/redis,splitice/redis,maodeyi/redis_lua,ramonsnir/redis,maodeyi/redis_lua,ramonsnir/redis,maodeyi/redis_lua