Adding UTF8 Subject support

UTF8 encoded subject passed by MailScanner is now saved in database, which has been converted to UTF8
create utf8 migration query and instructions
fix header decoding
specify dependency of Perl Encoding::FixLatin
Merge pull request #130 from mailwatch/utf8-subject

Deal with UTF-8 encoded subjects
Amend closing down messages to match reality

SQL Black/whitelist closing down messages referred to the 'per domain' spam blacklists instead of the SQL Blacklist/Whitelist
update changelog
Suppress a few warnings, tidy up

Fixed to not generate warnings when it can't properly parse input, slight tweak to garbage collection