Additional options to add to the dhcpd v4 and v6 configuration files
As of right now the gui for the DHCP server (both v4 and v6) does allow for a limited number of global options. For example if i want to use the "ddns-dual-stack-mixed-mode true" configuration parameter I have to modify the services.inc file to write the dhcpd config under a different name (dhcpd.conf.auto for example) and then manually edit the dhcpd.conf file. I propose a Custom option box in dhcp server (both v4 and v6) for global configuration parameters. Same solution as in the DNS Forwarder service.