To make it easier to deploy a host with static ip configuration foreman should know
1. wether the host uses dhcp or not
2. the default router for the host's subnet
3. the nameserver the host should use

Information should be available in templates as @host.gateway and @host.nameserver (or maybe @host.nameserver1 and @host.nameserver2).

The information wether DHCP is to be used or not should be configurable on a host level. If absent it should default to "yes" if the host's subnet has a DHCP smart-proxy, "no" otherwise.
The information for the default router should be configurable per subnet
The information for the nameserver should be configurable per subnet (I'm not really sure this is a good idea, but usually a nameserver is either reachable from a subnet or not so per-subnet seems reasonable)