add vagrant style build for go_segment

This PR is to build a base box for go_segment to speed up our Jenkins build times. We were not able to get the packer approach to building boxes working, because of the private SG cookbooks. Instead we used Vagrant, Berkshelf, and `vagrant package` to build the box, see the README in `go_segment_base` directory.

Let me know if there are questions or feeback, or if you prefer I PR this to a topic branch since it's so different.
I'm wondering if we should wrap some or all of these into a thor task?  The part I really don't like is the manual --output value.  It'd be much better if things like chef version and centos version were somewhere and used in both the Vagrantfile/recipes as well as in a thor task running vagrant package.