add failing test for smart collector issue #292
dynamically find first attribute line of smartctl output

Warnings can add lines to header so do not assume the attributes
always start one the 8th line.

Fixes #292.
log missing header at WARN instead of DEBUG
fix publish API usage
switch to publish_gauge, fix loadavg equal always zero
Merge pull request #297 from bclermont/diskspace-publish-fix

fix publish API usage
Merge pull request #294 from bfritz/292-smart-collector-stops

292 smart collector stops
Merge pull request #298 from bclermont/loadavg-publish-fix

switch to publish_gauge, fix loadavg equal always zero