Fix heat purge deleted cron job

The cron job was sending errors to root's mailbox. Errors are
now directed to syslog.

The job couldn't find heat-manage. Added PATH and included
/usr/local/bin where heat-manage is located.

Change-Id: I31f28ac741731018d5be7943d0a336c99a909562
Closes-Bug: 1369755
Merge "Fix heat purge deleted cron job"