[Dovecot] v2.0.17 released

http://dovecot.org/releases/2.0/dovecot-2.0.17.tar.gz http://dovecot.org/releases/2.0/dovecot-2.0.17.tar.gz.sig

Among other changes:

+ Proxying now supports sending SSL client certificate to server with
  ssl_client_cert/key settings.
+ doveadm dump: Added support for dumping dbox headers/metadata.
- Fixed memory leaks in login processes with SSL connections
- vpopmail support was broken in v2.0.16