- Remove OpenDMARC
- Configure Rspamd for DMARC handling
- Update services and how to set up DNS records in README

Instead of registering a handler to run when the database is created,
register a variable and check it immediately to run the schema import.
This avoids a problem where an error between database creation and
schema import 1) leaves the server in a broken state, and 2) rerunning
the playbook doesn't fix it.

An earlier commit started transitioning opendmarc to use postgres, but
this was incomplete.  This patch reverts that change and uses mysql for
the reporting database.

Other changes:

* Do not maintain a copy of the database import schema.  A copy is
  included in the distribution in /usr/share/doc, so that is used
  instead.
* The configuration file is replaced with the distribution's sample
  configuration.  A second patch will restore the actual configuration.
  This will make the changes easier to see if the default configuraton
  file changes in future versions of opendmarc.

The package solr installs and uses tomcat7.  Installing tomcat8 appears
to be a mistake for Debian Jessie.

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).