updating vagrant fullstack to use empanada

vagrant/release/fullstack/Vagrantfile

@@ -3,10 +3,9 @@ CPU_COUNT = 2
 
 Vagrant.configure("2") do |config|
 
-  # Creates a devstack from a base Ubuntu 12.04 image
-  # TODO -- replace this with the base box that has edx_ansible and fullstack installed
-  config.vm.box     = "precise64"
-  config.vm.box_url = "http://files.vagrantup.com/precise64.box"
+  # Creates an edX fullstack VM from an official release
+  config.vm.box     = "empanada"
+  config.vm.box_url = "http://edx-static.s3.amazonaws.com/vagrant-images/20131218-empanada-fullstack.box.md5"
 
   config.vm.network :private_network, ip: "192.168.33.10"
   config.hostsupdater.aliases = ["preview.localhost"]