JPA listener injection test

Sample for JPA Listener injection. This works neatly, however...

> From the JPA 2.1 spec, 3.5.1 Entity Listeners:
>> Entity listener classes in Java EE environments support dependency injection 
>> through the Contexts and Dependency Injection API (CDI) [ 10 ] when the 
>> containing archive is a bean archive. An entity listener class that makes use of CDI 
>> injection may also define lifecycle callback methods annotated with the PostConstruct 
>> and PreDestroy annotations. These methods will be invoked after injection has taken 
>> place and before the entity listener instance is destroyed respectively

Only `@Stateless` and `@EJB` pair worked for me (tested wildfly CR1), while I'd expect `@Named` and `@Inject` should be working as well. That left be a bit puzzled but the sample shows the case.