Make smembers isMasterOnly = false

[fehmicansaglam]

Fixes #231
SMEMBERS is a read only command therefore it should be run on slaves.

[coveralls]

Coverage increased (+0.06%) to 90.508% when pulling fcfc71d on fehmicansaglam:master into 5600b00 on etaty:master.

[farico]

any updates on this PR and issue @etaty ?

[farico]

Temporary solution would be to use slavesClients directly on RedisClientMasterSlaves:

val redis = RedisClientMasterSlaves(...)
redis.slavesClients.smembers() // send SMEMBERS to replicas