Enhance RunWatcher notifications and ArtifactParams feature

In this release, I revised the way I associate test method Description objects to atomic tests to ensure that the notifications I send to RunWatcher service providers include the descriptions that were used when the associated methods were actually invoked. This resolves an inconsistency related to the JUnitParams test runner.

I also enhanced the ArtifactParams feature, adding code in RunReflectiveCall to record the "callable" object in the AtomIdentity test watcher. This object is a closure which may contain the parameters that were supplied to the actual test method. This enhancement can greatly simplify the implementation of the getParameters() method of the ArtifactParams interface.