Always add the request_id to the msg.

This changes the sidekiq client middleware to always add the request id to the msg, if it's available. This allows us to see the request_id that kicked off a job when the job fails.

Actually logging the request_id is still only enabled when sidekiq_options includes `log_request_id`.

![](https://s3.amazonaws.com/ejholmes.github.com/E5H4g.png)