cronie: enable multi-user crontab usage and make cron environment complete
fix [BUGID #673]
several cron related test cases in LTP reveals that our current cron recipe
is not complete:
a) a complete cron hierarchy better have:
/etc/crontab
/etc/cron.d
/etc/cron.hourly
/etc/cron.daily
/etc/cron.weekly
/etc/cron.monthly
b) for a normal user to use crontab command:
add a new group - crontab
/usr/bin/crontab is setgid to root:crontab
/var/spool/cron is owned by root:crontab
below are optional, and thus not included in the default setup:
/etc/cron.deny
/etc/cron.allow
cronie by default only allows root user to use crontab, if neither cron.deny
nor cron.allow exists. They are controlled by final policy deployed on the
product.
