Clean up autoFiles in tests and check they were cleaned

This is mainly to catch if there is some condition that
leaves it impossible to clean up autoFiles, but also keeps
multiple test runs from leaving large amounts of temp files.
Fix the file clean up routine

This fixes the file clean up routine, as there are some cases where
calling destroy on a writable stream will close the file immediately
and the following code will not delete the file since it now looks
like the file was never opened.
Merge pull request #59 from dougwilson/fix/auto-files-cleanup

File the autoFiles cleanup routing