Log Message:
update dovecot to 1.0beta8.

changes since 1.0beta7:

        * Fixed a security hole with mbox: "1 LIST .. *" command could
          list all directories and files under the mbox root directory, so
          if your mails were stored in eg. /var/mail/%u/ directory, the
          command would list everything under /var/mail.
        + Unless nfs_check=no or mmap_disable=yes, check for the first login
          if the user's index directory exists in NFS mount. If so, refuse to
          run. This is done only on first login to avoid constant extra
          overhead.
        + If we have plugins set and imap_capability unset, figure out the
          IMAP capabilities automatically by running imap binary at startup.
          The generated capability list isn't updated until Dovecot is
          restarted completely, so if you add or remove IMAP plugins you
          should restart. If you have problems related to this, set
          imap_capabilities setting manually to work around it.
        + Added auth_username_format setting
        - pop3_lock_session setting wasn't really working
        - Lots of fixes related to quota handling. It's still not working
          perfectly though.
        - Lots of index handling fixes, especially with mmap_disable=yes
        - Maildir: saving mails could have sometimes caused "Append with UID
          n, but next_uid = m" errors
        - flock() locking never timeouted because ignoring SIGALRM caused the
          system call just to be restarted when SIGALRM occurred (probably not
          with all OSes though?)
        - kqueue: Fixed "Unrecognized event". Patch by Vaclav Haisman