Certificate management

Issue description

Since Topincs takes control over the domain other ACME certificate management are only usable with Apache config manipulation. Thus it is probably easier to do it in Topincs with a new command "certificate". When called from the command line it ensures that the certificate is valid for some time. Additionally add a CRON job.

Developer comments

Two new general commands were introduced: [https://www.topincs.com/adminreference/acme-issue, acme-issue] and [https://www.topincs.com/adminreference/acme-renew-all, acme-renew-all].