You can't re-run the integTest target in gradle's build without cleaning it each time. It takes a really long time to run now, so this is a pain.

There are two problems with this that I saw:

• The integTest.doFirst closure that copies over the explodedDist lib directory doesn't delete the old gradle*.jar files first, so you get duplicates.
• The SamplesJavaMultiProjectIntegrationTest does not properly clean itself up, so it can't be re-run. It attempts to clean up in its setup method, but has a bug and specifies the wrong directories to delete.

This patch should correct both of these issues.