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.

Resolves #400.

Resolves #410.

 * fix mail_db_opendmarc_username/mail_db_opendmarc_password variable
   not found.
 * python-mysqldb package is required. Add it to opendmarc task.