The double persistence.xml in JSF and REST projects was causing
problems in some environments, as the tables were created twice.

This commit fixes this error by moving the persistence.xml to the
service layer.

The REST API methods for entity creation and modification have been
simplified with more basic entities.

In addition, the UserResource class has been added so that it is
possible now for clients to use it for user authentication.

Missing version for compiler, javadoc, source and deploy plugin in POM was
causing some warning messages during the compilation with Maven.

In addition, the Javadoc was fixed in the OwnerService and PetService
classes.

The addition of the jboss-ejb3.xml file with the security domain
configuration allows the deployment of the "services" project as an
independent project in a Wildfly/JBoss container.

The REST layer has been added but with incomplete tests. Students will
have to complete the tests.

This commit includes an important refactorization regarding tests. Test
classes and datasets have been moved from the "service" project to a new
"tests" project. This way, any project can include this "tests" project
as a dependency in order to have access to these common testing
resources.

This commit adds the OwnerService and PetService EJBs to the
implementation. This commit also includes the tests for this EJBs with
two different Wildfly profiles: a H2 profile and a MySQL profile.