[Dovecot] v2.0.21 released

[Timo Sirainen]

http://dovecot.org/releases/2.0/dovecot-2.0.21.tar.gz
http://dovecot.org/releases/2.0/dovecot-2.0.21.tar.gz.sig

        + dict: file backend supports now also fcntl/flock locking optionally
        - imap-login: Memory leak fixed
        - imap: Non-UTF8 input on SEARCH command parameters could have crashed
        - auth: Fixed crash with DIGEST-MD5 when attempting to do master user
          login without master passdbs. 
        - sdbox: Don't use more fds than necessary when copying mails.
        - mdbox kept the user's storage locked a bit longer than it needed to