Initial support for user clustered workers

Adds a Worker interface with two implementations, LocalWorker runs the test in a Goroutine, redis.Worker send a redis message to trigger the benchmark on a remote node. redis.Slave has some code to pull tasks off the queue, benchmark them, and then reply via redis with the result of the benchmark. 

Can probably do this much better, e.g. with one reply connection feeding in results rather than a reply connection for each slave, but this is a start.