ISPN-3028 Add tests for example configuration files

The overall testsuite is run by default even though the example-configs tests are disabled by default.

The test suite runs by default because later there might be tests that we want to run every time the server is built. The test suite run can be disabled by -Dno.tests:

mvn clean package -Dno.tests

To run the example configuration tests:

mvn clean package -Dts.example-configs

...these tests take 3-5 mins so they're disabled by default.

Let me know what you think, thanks.

Martin