Multiply updates

  * Add simple post-processor,
    for predictable qemu artifact naming
  * install-recommends false for ubuntu16
  * Fix zerofree for lvm based

Change-Id: Ic87d0c5e9472894714294a27d4aef797474138c6
diff --git a/day01-image/template.json b/day01-image/template.json
index 741b7b6..881516e 100644
--- a/day01-image/template.json
+++ b/day01-image/template.json
@@ -107,6 +107,16 @@
       "destination": "/etc"
     }
   ],
+  "post-processors": [
+    {
+        "keep_input_artifact": false,
+        "output": "images/{{ user `image_name` }}.qcow2",
+        "type": "vagrant",
+        "only": [
+           "qemu"
+      ]
+    }
+  ],
   "builders": [
     {
       "type": "qemu",