A lot of exceptions during cleanup

[Salatich]

I've noticed that some extra folders like "spark-uuid" in System.getProperty("java.io.tmpdir") are created. But, some of them are not deleted. Problem is somewhere here https://github.com/holdenk/spark-testing-base/blob/79eef40cdab48ee7aca8902754e3c456f569eea6/core/src/main/1.3/scala/com/holdenkarau/spark/testing/Utils.scala#L109, it returns true, file is not deleted.

I read a bit about java.io.File#delete - seems that file cannot be deleted by two general reasons: permissions and busying by some process. So, since some of them are deleted - looks like permissions is not the reason. It's really annoying to collect megabytes in temp directory.

Spark version 2.2.1, scala version 2.11

Any thoughts here?