Add new file to display current kernel info. Related to comment !789 (comment 63987)

Make traffic quota datas available for template

every cron execution. The logfile can be disabled by using -NoLog

We do only trigger a rewrite of the zonefile by touching server log so no need to chank against existance of a file.
Thanks to Tom Albers who pointed me to this issue by providing an excellent bug report!

Also removed some garbage

instead we are now using dynamic purging of the logs.

add functions to 550-bind_dnssec.inc.php (see https://www.howtoforge.com/community/threads/dnssec-problem-expire-too-soon-ispconfig-3-1.74682/#post-351381)

DNSSEC-Cronjob should only run on ispconfig master as we are working with datalog and not accessing things directly

https://www.howtoforge.com/community/threads/quota-warnings-notifications.73747/#post-347405