Static report generation

[vkorn]

Following up on reddit discussion.

Not sure if anything else uses coverage report this way, but that's how we setup our build process:

1. Run linter/tests
2. Package/dockerize everything
3. Cleanup the coverage (usual cat cover/cover.tmp.out | grep -v ".pb.go" >> cover/cover.out)
4. Generate html report and publish it as a build artifact, later available through the deployment pipeline

Default go cover html looks, well, bad and doesn't have information about tests themselves. The view gokiburi is way more informative. It would be amazing if we can run gokiburi instead of test/coverage and have a single html file as an output. With packages/tests/coverage details.

[michenriksen]

Thanks for writing it up in here! I think it's a really cool idea. It sticks a bit outside what I see the main Gokiburi tool being for now, but I can definitely see this being a small, CI-friendly auxiliary tool for Gokiburi that I will look into.