If notifications are enabled in the config, Adds a eventHandler
accepting Notification{} payloads to the internal Bus.  The
eventHandler then marshals the payload into json and sends it
to a rabbitmq topic exchange using the
Notification.Priority+Noticiation.EventType as the routing key.
eg.  INFO.account.created

Currently, notifications are only being emitted for
INFO.account.created
INFO.account.updated
INFO.user.created
INFO.user.updated