Adds support for YubiHSM

Setting up the YubiHSM for this purpose was a bit fiddly, but the README.md should contain necessary steps to get it running. It's important to note that every time YubiHSM is removed from the server it needs to be unlocked before use.

Also notice that this PR changes the parameters.yml.dist structure, so update on a local parameters.yml is needed.

Questions or feedback, let me know.