nut-monitor: Configure upsmon

`upsmon` is the component of [NUT] that monitors (local or remote) UPS
devices and reacts to changes in their state.  Notably, it is
responsible for powering down the system when there is insufficient
power to the system.

group_vars/nut-monitor.yml

@@ -0,0 +1,11 @@
+nut_monitor:
+- system: apc1300@nut.pyrocufflink.blue
+  powervalue: 1
+  username: '{{ ansible_hostname }}'
+  password: '{{ nut_monitor_password }}'
+- system: apc1500@nut.pyrocufflink.blue
+  powervalue: 1
+  username: '{{ ansible_hostname }}'
+  password: '{{ nut_monitor_password }}'
+nut_monitor_minsupplies: 1
+nut_monitor_shutdowncmd: /sbin/shutdown -h +0