Improve Author-Book Relationship in Acumen and Plone GH3050
In some cases, we have a contributor who has one role on one book and another role on another book (e.g. "by" and "Foreword by"). In these cases we end up with multiple contact records for the same contributor. In Plone, we have this covered with the "member," "book," and "book roster." In Acumen, we need to be sure that we have only one contributor record and use the "override role" field when their contribution is different from their primary role.