Configure ipa_dns DS plugin on install and upgrade
    
    The plugin is configured unconditionally (i.e. does not check if
    IPA was configured with DNS) as the plugin is needed on all
    replicas to prevent objectclass violations due to missing SOA
    serial in idnsZone objectclass. The violation could happen if just
    one replica configured DNS and added a new zone.
    
    https://fedorahosted.org/freeipa/ticket/3347