cyberdojo/grafana docker image

• The source for the cyberdojo/grafana Docker image.
• A docker-containerized micro-service for https://cyber-dojo.org.
• A monitoring service running on port 3000.

Inside grafana, the data-source is provided by the prometheus service. Set the name to ${DS_PROMETHEUS}, the Url to http://cyber-dojo-prometheus:9090/ and the Access to proxy.