Prometheus Support

[onelapahead]

With hyperledger/firefly#321, firefly will now have a metrics section in its config file for configuring the Prometheus metrics server it comes with.

ff needs to be updated to include templating / generating this section of config. And then as a potential enhancement to the local dev experience, I think it would be great if we had a CLI option to also standup a Prometheus and Grafana via docker-compose when starting a stack. These would automatically know to scrape all FireFlys w/in a network for metrics.