Lets you inject in a RedisConnect into Sidekiq::Client so you can push j...

...obs to different Redis instances in the same application.

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We're causing 100% CPU utilization in our Sidekiq Redis instance during peak load, sometimes we're handling over 8,000 jobs/second. We're using dedicated hardware and a beefy machine and the only purpose of the instance is Sidekiq, but there's only so much a single core can do. 

We're going to partition out our Sidekiq and start pushing some queues to different instances. This pull lets you at least construct your own `Sidekiq::Client` that can point at any `RedisConnection`. A subsequent modification would to do something like `MyJob.with(:connection => conn).perform_async()` which could then dynamically handle this, but for now this will certainly suffice.