Preserve symlinks when zipping final app

Without preserving symlinks, final app which include vendored frameworks can become huge. The internal structure of frameworks is full of symlinks, which are replaced by copies of symlinked files when zipping without --symlinks option.
Merge branch 'master' of https://github.com/whomwah/motion-sparkle into whomwah-master

* 'master' of https://github.com/whomwah/motion-sparkle:
  Update README.md
  add package_url option
  add package_url option
add more url configuration options, building on #6