home-assistant: Configure BURP backups

Take a snapshot of the history database first, then back up everything
in `/var/lib/homeassistant`.

group_vars/home-assistant.yml

@@ -8,6 +8,7 @@ mosquitto_listeners:
 - port: 1883
   address: ::1
 mosquitto_password_file: /etc/mosquitto/passwd
+mosquitto_acl_file: /etc/mosquitto/acl
 apache_default_ssl_vhost: false
 homeassistant_server_name: homeassistant.pyrocufflink.blue
 homeassistant_update: false
@@ -17,3 +18,8 @@ zigbee2mqtt_update: '{{ homeassistant_update|bool }}'
 collectd_df:
   FSType: overlay
   IgnoreSelected: true
+
+burp_backup:
+- include: /var/lib/homeassistant
+
+burp_backup_script_pre: /etc/burp/backup-pre.sh