Shut down datasources in tests

[rPraml]

I noticed, that datasources are created, which aren't shut down.
This causes JUnit to wait up to 30 seconds after the last test was executed before it will kill the VM

Before this change

$ mvn test

// sometimes this error occurs:
[ERROR] Surefire is going to kill self fork JVM. The exit has elapsed 30 seconds after System.exit(0).

Tests run: 72
Total time:  46.631 s

After this change

$ mvn test

Tests run: 72
Total time:  14.866 s

This PR has only changes in test code

[rPraml]

@rbygrave JFYI:
The wait is caused by H2 here. It has an OnExitDatabaseCloser shutdown hook which will wait up to 4 seconds until an open connection will be killed. Maybe it would be a good idea to add such a listener also to ebean-datasource, which shut down all datasources