WIP Deoccupy root's crontab

[andrey-utkin]

Put subdomain TLS certificate renewal jobs to a /etc/cron.d/ file with a name which clearly marks its association.

Unobtrusively clear root's crontab from the remaining job entries.

[andrey-utkin]

I didn't notice debian/bluecherry.cron while I was working on this change:

 $ cat debian/bluecherry.cron
# m h dom mon dow user          command
0   0  *   *   *  bluecherry    /usr/share/bluecherry/backup_db.sh
30   0  *   *   *  bluecherry    curl -k https://localhost:7001/subdomainprovidercron

 $ ag bluecherry.cron
scripts/build_helper/post_make_install.sh
36:cp    ${SRC_PATH}/debian/bluecherry.cron ${DST_DIR}/etc/cron.d/bluecherry

[andrey-utkin]

The change lives on in https://github.com/bluecherrydvr/bluecherry-apps/pull/638/commits