Update update_bad_phishing_sites

Patched to compute some current update information if the TXT record at emails.msupdate.greylist.bastionmail.com is missing or out of date.

This pull request submitted per request at <http://lists.mailscanner.info/pipermail/mailscanner/2013-July/100851.html>. I have reconsidered my objection at <http://lists.mailscanner.info/pipermail/mailscanner/2013-July/100851.html> since it doesn't appear that the process that updates the TXT record for emails.msupdate.greylist.bastionmail.com will ever be fixed.