Build ISO with main MediaWiki-Vagrant required files

This includes:

* MediaWiki-Vagrant itself (cloned from your copy)
* MediaWiki core (cloned from your copy)
* VirtualBox (versions for various OSes)
* Vagrant (versions for various OSes)
* Ubuntu base box for VM
* YAML configuration for where to get the installers and supporting
  files
* Simple README and LICENSE files for people using the contents of the ISO

Bug: 61060
Change-Id: Ia9a4fd994294ee71ec3d3893418c941f809fb14c