Add packaging of a .zip file that has Windows line-endings, and remove the packaging of a .tar.gz.
Add packaging of a .zip file that has Windows line-endings, and remove the
packaging of a .tar.gz.

* dist.sh:
  (prepare_directory): new function to do basic preparation and
    verification of the release
  (...): export and package twice. remove .tar.gz packaging.

jandre/serf,jandre/serf,jandre/serf,jandre/serf