#4 Add 8 to the cyrusv3 mailer flags

[Dilian Wesselinov Palauzov]

The Sendmail Installation and Operations Guide defines the “8” mailer flag as

If set, it is acceptable to send eight bit data to this mailer; the usual attempt to do 8->7 bit MIME conversions will be bypassed.

Cyrus IMAP/lmtpd announces the 8BITMIME extension.

I propose adding the 8 flag to the cyrusv3 mailers.