Adds verbatim dataum to collecting events.  Adds not-null constraints to polymorphic relationships.
Moving towards better housekeeping patterns.
Hybrid database/validation examples for creating identifiers and notes while maintaing data integrity.
Refactoring Source::Bibtex vs. roles creation patterns.
Refactoring to correctly build related polymorphic objects.  There are examples in identifiers_spec as to how to build identifiers.  @BethFrank Source::Bibtex now has a create_authors_editors rather than build_, tests have been updated throughout.