Graph testing results over time MVC

Report https://news.ycombinator.com/item?id=11092066

Show a code coverage graph a tab on https://gitlab.com/gitlab-org/gitlab-ce/graphs/master/

Consider sending back other metrics such as performance and graphing those as well.

Ideally we do this in a way that makes it easy for developers to output/post a "generic" metric to the repo in a way that ANY metric can be recorded over time.

Open Tracing is the standard format - "Open Metrics". What if we build this on that? https://openmetrics.io/

• CI job generates open-metrics.txt
• We log those metrics generically
• We display a graph of those over time