Allow relative paths for certificates

Thank you for fixing / testing this.

There seems to be nothing against relative file paths. I'm guessing (half from memory) that I was just 'lazy' while doing a confusing rewrite from a strange earlier SP key/cert config that did require absolute paths... and that I just stuck to the existing restriction and delayed thinking about relative paths until "later".

Thanks a bunch @roderik, nice to have these relative for portability between systems

Automatically closed - issue fixed for 2 weeks with no activity.