Add new shell script for configuring VMs with CoreOS rkt. Modify Vagrantfile to "pre-download" files if they exist in current directory. Add new multi-platform code to Vagrantfile. Change filenames to adhere to new naming convention.
Add Ruby code to determine full path to supporting files referenced
in all Vagrantfiles. This will allow more effective use of Vagrant
commands when not in the same directory as the Vagrantfile.