Allow everything from 'self' in CSP header. This will allow to play
media etc...

Redis uses `-` in configuration parameters which counts as a word
boundary in regural expressions

To not collide with rsnapshot_btrfs file system backups

find works with exclusive time periods so 6 days or older and 27 and
older needs to be removed

In case /var/lib/mysql is a root of ext filesystem, lost+found directory
is wrongly treated as database with given name.

https://bugs.mysql.com/bug.php?id=22615

An extreme situation in previous state could happend, that daily backup
starts just a minute after hourly backup starts.

By spanning hourly backups across 35 minutes and start other from 45 and
later, we give 10 minutes at least to hourly backup to finish.

We also add 5 minutes before every whole hour to let system take care of
removed backups (snapshots).

And uninstallation task in case of mail delivery is not enabled

Conditioning virtual users configuratoin by mail_delivery_enabled flag
was not actualy correct

exim is not needed anymore, postfix does its work