- managesieve :: this allows sieve filters to be edited through a
  brower
- twofactor_gauthenticator :: allow optional two-factor authentication
  when logging into webmail
- carddav :: sync ownCloud contacts with roundcube

Baseline the configuration file distributed Roundcube 1.4.1 before
modification for sovereign.

Roundcube is not available on Jessie except in backports.  This role is
also out of date and needs reviewed and updated for the release included
in backports.  Roundcube could alternatively be installed from source as
recommended by the maintainers.

See https://wiki.mozilla.org/Security/Server_Side_TLS for details.
Removes RC4 cipher. Fixes issue #341.
Also explicitly disabled SSLCompression and enables OCSP stapling.

We should put all these settings in
/etc/apache2/mods-enabled/ssl.conf
to avoid duplication...

Remove all configuration for MySQL and configure PostgreSQL as the main
database.

All *_mysql_* options have been changed to *_db_* options.

Postgres requires the database user to have a password in order to
connect via localhost. The db_admin_password option is used to set the
password of the admin user (usually postgres).