Log Message:
Update to Dovecot 1.2.8.

* Dovecot v1.2.x had been creating base_dir (and its parents if
  necessary) with 0777 permissions. The base_dir's permissions get
  changed to 0755 automatically at startup, but you may need to
  chmod the parent directories manually.

- acl: If user has rights from more than one group, merge them instead
  of choosing one group's rights and ignoring others.
- virtual: When using a lot of mailboxes, the virtual mailbox's header
  could have grown over 32 kB and caused "out of memory" crashes. Also
  over 64 kB headers couldn't even be updated with existing transaction
  log records. Added a new record type that gets used with >=64 kB
  headers. Older Dovecot versions don't understand this header and
  will log errors if they see it.
- FETCH BODYSTRUCTURE didn't return RFC 2231 "key*" fields correctly

Plus some small documentation issues for dovecot-managesieve.