Named return variables should only be used to describe the returned type
further, e.g. `err error` doesn't add any new information and is just
stutter.
Instead of doing the whole metric exposition in a platform specific collector
implementation, this creates and updates the metrics in meminfo.go and
expected a platform specific implementation of getMemInfo on
*meminfoCollector.
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.
