Upgrade to concourse-java-scripts 0.0.4

[snicoll]

We need to make sure spring-io/concourse-java-scripts#11 is merged first.

When we upgrade we need to revert the workaround we've added for that issue.

[snicoll]

I've moved this to 2.1.x as we'd need this as well in case we should ever release 2.1.x again.

[wilkinsona]

Isn't this still needed as we're using 0.0.3 at the moment?