More reliable HTTP server based on Ruby

Ruby was used as the basis because, if you're using Vagrant, you'll
probably have it installed.
Remove the note about netcat
Further improvements to Ruby HTTP server

  * Server should always find a free port now.
  * Clearer defined states in operation.
    - Stop listening on the socket past 1024 as payload should have
      been delivered by that point.
    - If the payload is <1024 bytes then *assume* it is a good
      request and send the kickstart file.
    - Anything else, assume is a 500.
  * Accepts a different name for the kickstart file.
Use Vagrant's Ruby else system Ruby else fail
Merge branch 'newhttpserver'

Provides a Ruby-based HTTP server from which to serve the kickstart
files.

Closes GH-13
Upgrade Guest Addition's version

Closes GH-17
Clarify copying situation
Add guidelines for committing
Make primary HDD size adjustable in vars.sh