Add support for Redis Sentinel

[JamieCressey]

To support a HA environment, return the Redis DB from a quorum of Sentinel instances.

I plan to work on a PR over the next couple of weeks.

[bjinwright]

Any movement on this?

[JamieCressey]

Unfortunately not. I don't think it's a massive change to implement so shouldn't take me (or someone else if they're interested) too long, I just don't have that time currently.

[bjinwright]

Ok thanks