Upgrades redis.

I don't think we should be so strict w/ version 0.8.x. Here's a big reason why we need the latest version of redis...

https://github.com/mranney/node_redis/commit/0b6870be5cab57315594fadd1fd205647b267932

If you are using redis in a before_perform plugin, and the callback fails, it won't be picked up by the worker's domain.