Migrated model tests, etc. from dul-hydra

Migrated from dul-hydra:
- model tests, factories and fixtures
- ActiveSupport::Notifications subscriptions
- ActiveFedora::Base and ActiveFedora::Datastream behaviors
- Predicate mappings config for ActiveFedora
Added jettywrapper
Added ci task
Added migrations for events and minted_ids tables
Added stub User model and migration to dummy app for testing