Revision 1837939

No longer produce SHA1 checksums for release tarballs.

Per ASF policy: https://www.apache.org/dev/release-distribution#sigs-and-sums

* tools/dist/release.py
  (roll_tarballs): Don't create .sha1 files.
  (get_sha1info): Rename to 'get_fileinfo'. Only return filenames.
  (write_announcement): Don't fetch SHA1 info.
  (write_downloads): Track the rename.

* tools/dist/templates/download.ezt,
  tools/dist/templates/rc-release-ann.ezt,
  tools/dist/templates/stable-release-ann.ezt
    Remove SHA1 listings.