Make Changes-and-Notes.sh and Release-for-upload.sh refer to the same references.
Update release instructions.
Credit dak180.
Add some comments to the requirements and use the right extension.
Completes the previous commit on extension correction.
Only keep a pair of public/private keys for DSA signing.

This key pair (vienna_private_key.pem / vienna_public_key.pem) is available to all project admins.
Merge pull request #134 from barijaona/build

Minor improvement to build process