Add support for a redis failover proxy

[ghost]

Redis supports master slave configurations and manual failover. Unfortunately, automated failover is unlikely to be added until the RedisCluster project is live for a while. In the meantime, one great solution is the redis_failover gem -> https://github.com/ryanlecompte/redis_failover - this adds a zookeeper backed redis node manager that can automate the slave failover in the event of a node going down. This did require some additional client work, as redis_failover includes a client with some 'smarts' to take advantage of the high-availability features. Would supporting a failover framework like this be something within the scope of scala-redis?

[joprice]

+1. If you need help moving it along, I could pitch in.

[debasishg]

Thanks .. I will take a look over the weekend and merge.

[mrubinwch]

@debasishg can you please add this support to the library?