adding fullstack readme and updating devstack Vagrantfile

vagrant/devstack/Vagrantfile

@@ -3,8 +3,7 @@ CPU_COUNT = 2
 
 Vagrant.configure("2") do |config|
 
-# For efficiency, we create custom base box from an Ubuntu 12.04 image
-# Once the custom base box is created, we use that as a starting point.
+# Creates a devstack from a base Ubuntu 12.04 image
   config.vm.box     = "precise64"
   config.vm.box_url = "http://files.vagrantup.com/precise64.box"
 

vagrant/fullstack/README.rst

+devstack
+========
+
+Vagrant instance for a production like configuration running all services on a single server
+
+Installation instructions - https://github.com/edx/configuration/wiki#installing-edx-using-a-pre-built-vagrant-fullstack-image