Path::Class::Dir does not recognize dir('.')->subsumes('CONTRIBUTING') - RT#90209
use a placeholder string when there is no bugtracker metadata set
use same plugins at minting time to generate content for these files
Dist-Zilla-PluginBundle-Author-ETHER-0.039

          - fix config for [Git::Commit], to properly commit files that were
            newly added to the dist
          - now generating full starting content for CONTRIBUTING, README.md,
            LICENSE when minting a new distribution