Clean up the "go test" output from "make test" to be much more readable/scannable

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Exclude more "definitely not unit tested Go source code" directories from hack/make/test

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #4612 from tianon/cleaner-test-output

Cleaner test output