Redis Cluster support improvement

[kjoe]

Maybe we can use universal redis client rather than separated files and build options (before document it):

https://godoc.org/github.com/go-redis/redis#UniversalClient

What do you think? It's much cleaner to use the same binary in different environments, but ScanKeys() needs some alteration too.

Thanks!

[SergeyTsalkov]

Seems reasonable to me, though I've not looked at it too closely. Any downsides to using UniversalClient?