Fix creation of reverse DNS zones.
    
    Create reverse DNS zone for /24 IPv4 subnet and /64 IPv6 subnet by
    default instead of using the netmask from the --ip-address option.
    
    Custom reverse DNS zone can be specified using new --reverse-zone
    option, which replaces the old --ip-address netmask way of creating
    reverse zones.
    
    The reverse DNS zone name is printed to the user during the install.
    
    ticket 1398