Draft: RELEASE Use gem-release CI component to automate releases

This repository supports our packaged release of mail_room that ships with GitLab. We strive to diverge as little as possible from the canonical upstream at https://www.github.com/tpitale/mail_room. If we do diverge, our patches are sent upstream for review and we carry them here to support the GitLab application.

Please direct any logic changes upstream to https://www.github.com/tpitale/mail_room.