This change uses p4 admin journal command against the master server to rotate the journal.
Added a p4d_truncate_journal to use in weekly_back that still rotates via p4d.
The purpose of this change is to allow you to run daily_backup.sh on a standby machine
where you have a shared depotdata volume. If you want to use daily on the standby machine,
you have to put offline_db on the shared depotdata volume which means you will NOT want
to run weekly_backup.sh on the master very often, but that is basically what Anton is
recommending now. I am currently testing this setup on a production environment, and if
it works well, I will change mkdirs.sh to put offline_db on the depotdata volume by
default and update the crontabs not to run weekly anymore.