FR: Add support to determine Gradle versions

[stefanneuhaus]

The use case I have in mind is to test a plugin against incompatibilities that are lurking in upcoming Gradle versions (RC, nightly). The IntegrationSpec already allows for testing a plugin against certain versions by specifying a gradleVersion. Currently every plugin tester has to write its own logic that determines e.g. the latest RC or nightly build. Integrating this logic into nebula-test would facilitate this a lot.

There is already a REST API (serving JSON) where this information could be retrieved from (just browse to the appropriate sub resource): Gradle Version Information

[scphantm]

As long as you can turn it off. I don't want that. We don't test against snapshots, why waste our time testing against fluctuating code we will never run? Ill wait a few weeks and run my tests against the release. My developers can wait a few weeks for the new version, they don't have to have it on release day.