CRUNCH-679: Improvements for usage of DistCp (#20)

* CRUNCH-679: Improvements for usage of DistCp

* CRUNCH-679: Fix NPE bug by preserving IOUtils.cleanup logic

* CRUNCH-679: CrunchRenameCopyListing's constructor needs to be public

* CRUNCH-679: Unset rename configuration after loading into copy listing

* CRUNCH-679: Reduce default max distcp map tasks from 1000 to 100

* CRUNCH-679: Update log message formatting
5 files changed