Create directory in $STORAGE_ROOT for bayes database.
Added --username arg to sa-learn as the user mail does not have permission to edit files in $STORAGE_ROOT. There is probably a better solution to this...
As the scripts keep growing, it's time to split them up to
keep them understandable.
This splits mail.sh into mail-postfix.sh, mail-dovecot.sh,
and mail-users.sh, which has all of the user database-related
configurations shared by Dovecot and Postfix. Also from
spamassassin.sh the core sieve configuration is moved into
mail-dovecot.sh and the virtual transport setting is moved
into mail-postfix.sh.
Also revising one of the sed scripts in mail-dovecot to
not insert a new additional # at the start of a line each
time the script is run.
