Catch error on startup about machinery

[randomandy]

Ok so I'm pretty sure it happens here:
broker.StartConsuming()
inside Launch()

[randomandy]

This fixes it:

func (worker *Worker) Launch() error {
    cnf := worker.server.GetConfig()
    broker := worker.server.GetBroker()

    log.Printf("Launching a worker with the following settings:")
    log.Printf("- Broker: %s", cnf.Broker)
    log.Printf("- ResultBackend: %s", cnf.ResultBackend)
    log.Printf("- Exchange: %s", cnf.Exchange)
    log.Printf("- ExchangeType: %s", cnf.ExchangeType)
    log.Printf("- DefaultQueue: %s", cnf.DefaultQueue)
    log.Printf("- BindingKey: %s", cnf.BindingKey)

    errorsChan := make(chan error)

    go func() {
        for {
            retry, err := broker.StartConsuming(worker.ConsumerTag, worker)
            if err != nil {
                errorsChan <- err
            }

            if retry {
                log.Printf("Going to retry launching the worker. Error: %v", err)
            }
        }
    }()

    return <-errorsChan
}

[RichardKnop]

@randomandy HI Andy. Thanks for catching this bug!

I'm quite busy at the moment so it might take me few days to take a look. If you want, create a PR with a fix and I will try to look at it and merge it this weekend if time allows.

[randomandy]

@RichardKnop Hey Richard. Sure thing, happy to help. Fix is in #76