Use -h --hostname instead (or in addition) to -s to match redis-cli, redis-benchmark...

[tgrall]

The memtier_benchmark tool is using the -s --server as a parameter to pass the server address.

It would be good to be consistent with other redis-* tools and use -h --hostname instead

[filipecosta90]

Fixes by #224 and released as part of https://github.com/RedisLabs/memtier_benchmark/releases/tag/2.0.0