Setup a Prometheus server in a docker container

[kabirkbr]

Subtask of #13

[kabirkbr]

Follow this guide: https://www.emnify.com/blog/2018/02/01/monitoring-with-kamon-1-0, just run prometheus in docker and see if it works.

[kabirkbr]

I suppose this is done -- Promotheus server is run via docker with this script: https://github.com/singnet/offernet/blob/master/analysis/scripts/start_servers.sh, but the next issue is to configure it propertly... see #23