Fix incorrect timespamt in grofer proc

time.Unix expects the time to be in seconds whereas gopsutil gives time in milliseconds

Fixes #104

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update

Checklist:

[x] I have read the contribution guidelines and followed it as far as possible.
[ ] I have performed a self-review of my own code (if applicable)
[ ] I have commented my code, particularly in hard-to-understand areas (if applicable)
[ ] I have run go fmt on my code (reference)
[ ] I have made corresponding changes to the documentation (if applicable)
[x] My changes generate no new warnings
[ ] Any dependent and pending changes have been merged and published