fix mirror-image output dir

 * Aligh to all other qemu-builds images

Change-Id: If093897413d24a8f3f8d6c705560a7e2cb044c49
diff --git a/mirror-image/template.json b/mirror-image/template.json
index 6c5f7b5..4b1b24f 100644
--- a/mirror-image/template.json
+++ b/mirror-image/template.json
@@ -148,7 +148,7 @@
         ]
       ],
       "vm_name": "{{ user `image_name` }}-{{ isotime \"200601021504\"  }}",
-      "output_directory": "images/{{ user `image_name`}}",
+      "output_directory": "images/{{ user `image_name` }}-qemu-{{ isotime \"200601021504\"  }}",
       "format": "qcow2",
       "accelerator": "kvm",
       "disk_size": "{{ user `disk_size`}}",