(issue54) Implement a privilege drop to execute the program after installation. This commit is extremly ugly as I accidentally worked in a working tree that was partially merged with default. To review the real change please check the commit that will merge this branch into default.

#!/bin/bash
cp $2 $3
echo -e \\r\\nS:$(openssl dgst -sha256 -sign $1 < $2 | base64 -w0) >> $3