WIP Add KVM host backup recipe

Add a recipe that configures scripts for live backups of VM images via
libvirt and borg.

site-cookbooks/kosmos_kvm/templates/backup_all_vms.sh.erb

@@ -0,0 +1,11 @@
+#!/bin/bash
+# GENERATED BY CHEF
+# DO NOT EDIT
+set -e
+
+echo "Backing up all VMs with kvm_guest chef role..."
+
+for domain in <%= @vm_domains.join(" ") %>
+do
+  /root/backups/backup_vm.sh $domain
+done