Patches to fix s3n:// filesytem quirks.

PTAL @etorreborre thanks. By the way I tried running the tests and keep getting the following message:
Internal error when running tests: `java.lang.OutOfMemoryError: PermGen space`

This is even after setting the flags: `SBT_OPTS=-Xms2048M -Xmx4096M -XX:MaxPermSize=2048m -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled`
If we add more cases to this method I think we should refactor it:

 - is the move needed?
 - is it on the same file system?
 - can we really move or do we need to copy?

I just want to make sure that we don't miss any condition. The whole thing is currently a messy boolean expression that doesn't make it easy to understand its correctness.