Update documentation
Replace 'return_failed()' with plain 'return'
Add error notification customization by using extending ErrorNotification.
Fixes method missing exception when selectedValueChanged closure is not set.
Extensible 'ErrorCleaner' for validation
Fixes PropertyChangeListener duplication in validation
Add destroyEntityManager()
Fixes EntityManager not created when calling simple-jpa methods from view
Fixes transaction propagation not working
@SimplaJpaTransaction can be configured to use Policy.PROPAGATE, Policy.NO_PROPAGATE, or Policy.SKIP