Default run configuration support

[nik9000]

I'd like to be able to configure defaults for run configurations. We do this now for IntelliJ. Without this we end up running tests in Eclipse with quite different parameters than gradle build. And some of them fail. Lately everything that uses Mockito has started failing. The fix for the IntelliJ users is to add an --add-opens when launching the test jvm. That works for Eclipse too, but we can't add it automatically.