Update to use the latest HellaRedis

This updates HellaRedis and how it is used. The latest HellaRedis
takes a hash directly so this allows removing the
`RedisConnection`. This also changes the testing to use the
`ConnectionSpy` provided by HellaRedis. This allows testing that
the configuration was properly used when building a redis
connection.

@kellyredding - Ready for review. I'll rebase my other branches off of this so they can use it.