cpdup - Add -VV to ignore mtime

cpdup - Add -VV to ignore mtime

* The cpdup -V option verifies the contents of the files even if the
  mtime is the same, but also (currently) recopies the file without
  bothering to verify the contents if the mtime is different, even if
  the contents is the same.

* Add an extension, -VV, which verifies the contents of the file and
  ignores mtime entirely.  A copy is only made if the ownerchip,
  flags, modes, or content differs.