Prune VM backups after every run

closes #439

site-cookbooks/kosmos_kvm/recipes/backup.rb

@@ -45,6 +45,11 @@ cookbook_file "/root/backups/backup_vm.sh" do
   mode "0750"
 end
 
+cookbook_file "/root/backups/prune_vm_backups.sh" do
+  source "prune_vm_backups.sh"
+  mode "0750"
+end
+
 # Search all guests and filter by presence on current host
 vm_domains = search(:node, "role:kvm_guest").map{|n| n["hostname"] } \
              & `virsh list --name`.strip.chomp.split("\n")