v0.2.4

Fixed

• The appliance build got one step further, and stopped on the step before.
  With /mnt finally writable, Packer refused to start: Output directory
  '/mnt/appliance/out' already exists. It must not exist. That refusal is a
  feature — it is how Packer guarantees it never writes over a previous
  build — and the preparation step was creating that very directory. It now
  creates only the parent and the temporary directory, and leaves out/ to
  Packer. Two failures in a row at the same place say something worth keeping:
  a workflow that has never run is a workflow that does not work, and the only
  way to know is to run it.