allow multiple master-server for a bind-slave

interface/web/dns/dns_wizard.php

interface/web/dns/form/dns_slave.tform.php

interface/web/dns/lib/lang/ar_dns_slave.lng

interface/web/dns/lib/lang/bg_dns_slave.lng

interface/web/dns/lib/lang/br_dns_slave.lng

interface/web/dns/lib/lang/ca_dns_slave.lng

interface/web/dns/lib/lang/cz_dns_slave.lng

interface/web/dns/lib/lang/de_dns_slave.lng

interface/web/dns/lib/lang/dk_dns_slave.lng

interface/web/dns/lib/lang/el_dns_slave.lng

interface/web/dns/lib/lang/en_dns_slave.lng

interface/web/dns/lib/lang/es_dns_slave.lng

interface/web/dns/lib/lang/fi_dns_slave.lng

interface/web/dns/lib/lang/fr_dns_slave.lng

interface/web/dns/lib/lang/hr_dns_slave.lng

interface/web/dns/lib/lang/hu_dns_slave.lng

interface/web/dns/lib/lang/id_dns_slave.lng

interface/web/dns/lib/lang/it_dns_slave.lng

interface/web/dns/lib/lang/ja_dns_slave.lng

interface/web/dns/lib/lang/nl_dns_slave.lng