DHCP Option definition fails at subnet level

Currently if the dhcp option number is above 100 (may be too low????) we will automatically create the option definition so that it can be used by the server.

option mydhcpoption code 150 = array of ip-address;

This currently only works for global level dhcp options and server level options that override globals.

This should also work for subnet and host level definitions of an option.

As it stands now it forces you to use global/server level options just to create the definition in the config file.