Remove special tags necessary for gmond and runit collectors. All
collectors get built. Selection of which collectors to use continues to
happen via parameter.
Switch to Update using the Collecter Collect interface, due to not knowing all
metricnames in all modules beforehand we can't use Describe and thus the full
Collecter interface.
Remove 'updates', it's meaning varies by module and doesn't add much.
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.
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
