Update to Dovecot 2.0.8.

* Services' default vsz_limits weren't being enforced correctly in
  earlier v2.0 releases. Now that they are enforced, you might notice
  that the default limits are too low and you need to increase them.
  This problem will show up in logs as "out of memory" errors.
  See default_vsz_limit and service { vsz_limit } settings.
* LMTP: In earlier versions if mail was delivered to user+detail@domain
  address, LMTP server always attempted to deliver the mail to mailbox
  named "detail". This was rather unintentional and shouldn't have been
  the default. lmtp_save_to_detail_mailbox=yes setting now preserves
  this behavior (default is no).

+ Added systemd support (configure --with-systemdsystemunitdir).
  Based on patch by Christophe Fergeau.
+ Replaced broken mbox-snarf plugin with a new more generic snarf
  plugin.
- dbox: Fixes to handling external mail attachments
- verbose_proctitle=yes didn't work for all processes in v2.0.7
- imap, pop3: When service { client_count } was larger than 1, the
  log messages didn't use the correct prefix. Last logged in user's
  prefix was always used, regardless of what user's session actually
  logged it. Now the proper log prefix is always used.
- MySQL: Only the first specified host was ever used

(ghen)