Add TLS/SSL context parameter to constructor

[BramVanDaele]

As supported by predis/predis : phpredis/phpredis@8144db3

Could you add the correct info to the constructor (similar to last PR for AUTH)

[tbtmuse]

@BramVanDaele I see no indication that this parameter is supported by RedisSentinel the commit you linked to is for an update to RedisCluster docs.