Add test kitchen support, with cavaets

This commit adds initial test kitchen support to this cookbook.

* It assumes that those who wish to use test-kitchen have a box named
 `macosx-10.9` already built and added on their local workstation.
 Said box should not have anything installed - it should be a base OS.
* build-essential is added via a Berksfile and included before
 `homebrew`, as it's required by homebrew (the project), but not by
 homebrew (this cookbook), since users may wish to install XCode on
 their own systems via the App Store.