Last login is disabled by default as it's broken on ubuntu 12.04
Interrupts is disabled by default as it's very granular and we'll have total interrupts from /proc/stat
Allow ignoring devices from diskstats, ignore ram and loop devices by default.
Use glog for logging.
Diskstats: Split out metrics, keep 'device' label
Meminfo: Split out metrics, one each. Convert kB to bytes.
Netstats: Split out metrics, keep 'device' label.
Interrupts: Stays the same. Not perfect, but should be rarely used.
Loadavg: Make it clear it's the 1m loadavg
Last seen: Not clear this belongs in the node exporter, as it's more a user
thing than a machine thing. Changed to absolute time rather than relative.
All stats now have appropriate counter/gauge type.
The gmond (Ganglia) exporter module exports many metrics not under our
control. They should all be prefixed in a common way to make it obvious
where they came from.
Fixes https://github.com/prometheus/node_exporter/issues/8
