Fix the error logging of the promhttp handler by connecting it to the
promlog setup.
* Switch to go-kit/log.
* Cleanup CHANGELOG.
Fixes: https://github.com/prometheus/node_exporter/issues/1886
Signed-off-by: Ben Kochie <superq@gmail.com>
* Move FreeBSD/DragonflyBSD out of meminfo add kvm.
This gives us SwapUsed, and everything under one roof.
* Fix typos per review.
* Update to use newer API.
* Remove premature optimization per PR feedback.