anchor.diff:  
   ## Example For Ubuntu Vivid Generation 2
   
  -If you are running Windows under virtualization, you may need to create
  -a virtual switch with an `External` connection type.
  +If you are running Windows under virtualization, you may need to create a
  +virtual switch with an `External` connection type.
   
   ### Packer config:
   
  
positive.code:     below.
  
  -   `http_port_min` and `http_port_max` (number) - These are the minimum and
      maximum port to use for the HTTP server started to serve the `http_directory`.
      Because Packer often runs in parallel, Packer will choose a randomly available
      port in this range to run the HTTP server. If you want to force the HTTP
      server to be on one port, make this minimum and maximum port the same.
      By default the values are 8000 and 9000, respectively.
  
  -   `iso_urls` (array of strings) - Multiple URLs for the ISO to download.
      Packer will try these in order. If anything goes wrong attempting to download
      or while downloading a single URL, it will move on to the next. All URLs
      must point to the same file (same checksum). By default this is empty
      and `iso_url` is used. Only one of `iso_url` or `iso_urls` can be specified.
  
  -   `iso_target_extension` (string) - The extension of the iso file after
      download. This defaults to "iso".
  
negative.code:     drives and dvd drives will also be scsi and not ide.
  
  -   `guest_additions_mode` (string) - How should guest additions be installed.
      If value `attach` then attach iso image with by specified by
      `guest_additions_path`.  Otherwise guest additions is not installed.
  
  -   `guest_additions_path` (string) - The path to the iso image for guest
      additions.
  
  -   `http_directory` (string) - Path to a directory to serve using an HTTP
      server. The files in this directory will be available over HTTP that will
  