[atlas] X.509 certificate monitoring

I do not find a lot of examples of X.509 certificate retrieving and analysis? I just committed <https://github.com/RIPE-Atlas-Community/ripe-atlas-community-contrib/blob/master/cert-expiration.py> which is useful for me when watching certificate expiration for anycasted sites (where the cert retrieved depends on the probe). Any other examples? And by the way, do not hesitate to submit your scripts to <https://github.com/RIPE-Atlas-Community/ripe-atlas-community-contrib> (fork and pull request, or open an issue with the attached script).