Add checking of bastion host
Tested my branch on tee.sigsum.org as follows:
$ sudo -u sigsumchecker /var/sigsumchecker/usr/src/checker.testing/main.py -m cron -c hour --nomail
$ sudo -u sigsumchecker /var/sigsumchecker/usr/src/checker.testing/main.py -m cron -c day --nomail
Works.
When I stop my witness the hour job gets an error as expected.
I also (manually) tried changing the bastion DNS name to something invalid, just to see that the hour job which expects to find a certificate then fails as expected.
So, seems to be working!