Add script to convert vdi to Vagrant box

This will allow a more reproducible way to create Vagrant boxes for development & QA use. Closes #71 (closed).

Here are my notes on how to use this:

• Convert vdi to vagrant box:

$ sudo bin/vagrant-package <image>

• Add box to vagrant:

$ vagrant box add --force freedom-maker package.box
$ rm package.box

• Generate Vagrantfile:

$ vagrant init freedom-maker

• Edit Vagrantfile to add forwarded port for HTTPS:

  config.vm.network "forwarded_port", guest: 443, host: 4430

• Bring up vagrant:

$ vagrant up --provider virtualbox

• Cleanup:

$ vagrant destroy