- drop dd call from code and reimplement a proper python handler
  with progress reporting for this
- actually write to target, currently we only write /tmp/test.img
  until everything works right
- make the shell wrapper script go away (should be gone with
  dropping dd)
- show the partition unmounting in the progress bar
- add automatic dowload option to image selection for the UME
  images from cdimage.ubuntu.com
