This merely makes it easy and fun to import all developer keys used over
the past year to your local GPG keychain. This will make the task of
reviewing merge commits for signedness much easier, especially if you
use a nicelog alias such as this one:
https://github.com/todb-r7/junkdrawer/blob/master/dotfiles/git-repos/gitconfig#L40
This does not handle automating checking for signatures as part of
Travis-CI -- for that, see PR #5337, a work in progress.
