Test that data-source can be defined in application.xml and used in persistence.xml.

Additional test modeled after the existing tests for a data-source in web.xml and the @DataSourceDefinition annotation. This time a data source (data-source element) in application.xml inside an EAR is tested.
JavaDoc on these examples are parsed as AsciiDoc. 

See https://github.com/javaee-samples/javaee7-samples/blob/master/jpa/criteria/src/test/java/org/javaee7/jpa/criteria/JpaCriteriaTest.java#L34 for example