Create a CI job to generate manpages

Our man pages must be generated manually and are often out of sync when code changes are made to applications or puppet settings (defaults.rb). We should create a CI job in the per-component pipelines, similar to how we do localization.

1. We need to add ronn as a gem dependency, only when running from bundler, not when installing puppet as a gem. Similar to what we do for gettext-setup.
2. We need to run bundle exec rake gen_manpages to update the man pages
3. If that succeeds, run git add man -m "..."
4. Ensure the job that does automatic merge ups always resolves the conflicts as ours.

/cc Maggie Dreyer, Branan Riley, Jorie Tappa, Garrett Guillotte