[Dovecot] v2.0.15 released

http://dovecot.org/releases/2.0/dovecot-2.0.15.tar.gz http://dovecot.org/releases/2.0/dovecot-2.0.15.tar.gz.sig

+ doveadm altmove: Added -r parameter to move mails back to primary
  storage.
- v2.0.14: Index reading could have eaten a lot of memory in some
  situations
- doveadm index no longer affects future caching decisions
- mbox: Fixed crash during mail delivery when mailbox didn't yet have
  GUID assigned to it.
- zlib+mbox: Fetching last message from compressed mailboxes crashed.
- lib-sql: Fixed load balancing and error handling when multiple hosts
  are used.