add lifecycle callbacks Entities and Biz objects

 EntityBiz invokes onAdd, onUpdate, and onDelete methods to inform
 subclasses that a lifecycle action is taking place on a domain object.

 VroomEntity invokes onCreate, onUpdate, and onDelete methods to inform
 subclasses that a lifecycle action is taking place on a domain object.

 VroomEntity also invokes onSaveDao and onDeleteDao to inform subclasses
 that a lifecycle action is taking place on a DAO.
Merge pull request #45 from adennie/entity-lifecycle-callbacks

add lifecycle callbacks Entities and Biz objects