Setup APIs for master-to->worker cluster comms

[ecumike]

Some APIs that will be needed for the queen server to manage the worker servers:

• Get number of workers and which URLs are being processed
• Pause all workers: Tell workers to not respawn, shutting them down after current work is finished
• Re-engage workers
• Adjust number of workers
• Query for known remote non-master servers
• Query & adjust workload on remote servers