Revert "Remove force_unlink workaround"

The fix is not released before chef-12.0.0
resolvconf bug #642222 fix for ubuntu 10.04
Merge pull request #5 from dennybaa/rebase

resolvconf bug #642222 fix for ubuntu 10.04
Add TODO to remove Ubuntu-10.04 fix on end of support
Fix rubocop warnings
Fix case in comments
Bump version to 0.2.5, update CHANGELOG
fixing to use resolvconf order, new systems should support it
version bump