MailScanner - now set to not scan zip files.

This does not affect clamd scanning of attachments.
openvpnclients - now adds a warning in the web management if a vpn link is down.
setupemail - replacement cron.hourly script for mailscanner

The cron.hourly script for mailscanner was managing to start another set
of mailscanner processes eventually resulting in the server running out of memory.