Upgrade special master zones to forward zones
    
    This upgrade is executed only if IPA version is older than 4.0
    Requires detection if 'idnsforwardzone' objectclass is presented in
    schema before schema is upgraded
    
    Design: http://www.freeipa.org/page/V4/Forward_zones#Updates_and_Upgrades
    
    Ticket: https://fedorahosted.org/freeipa/ticket/3210
    Reviewed-By: Martin Kosek <mkosek@redhat.com>