roles/hass-dhcp: Deploy DHCP server for HA

The *hass-dhcp* role installs dnsmasq and configures it to serve DHCP
requests on the Home Assistant network. Since this network is not
routed, the regular DHCP relay/server setup will not work.

roles/hass-dhcp/tasks/main.yml

@@ -0,0 +1,14 @@
+- name: ensure dnsmasq is installed
+  package:
+    name: dnsmasq
+    state: present
+  tags:
+  - install
+
+- name: ensure dnsmasq is configured for homeassistant
+  template:
+    src: homeassistant.dnsmasq.conf.j2
+    dest: /etc/dnsmasq.d/homeassistant.conf
+    mode: '0644'
+  notify:
+  - restart dnsmasq