Changes

New release script: promote-to-release.sh

This is essentially a simplified variant as it only copies the aggregated folder
and creates the symbolic link in the deployment root dir.

The remote shell commands kicking-off release promotion on the server
from our home-machine, jenkins-builds/promote-to-release-ssh-*.sh
do pull the resulting sha512sum.txt, gpg-sign it
and push the sha512sum.txt.sig back to the server.

This allows full data integretiy over all aggregrated files
having their sha512 stored in the sha512sum.txt