Merge pull request #962 from edx/han/Vagrantfile

Use vagrant-vbguest plugin to sync VirtualBox Guest Editions versions

vagrant/release/devstack/Vagrantfile

@@ -61,6 +61,10 @@ Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
     # http://askubuntu.com/questions/238040/how-do-i-fix-name-service-for-vagrant-client
     vb.customize ["modifyvm", :id, "--natdnshostresolver1", "on"]
   end
+ 
+  # Use vagrant-vbguest plugin to make sure Guest Additions are in sync
+  config.vbguest.auto_reboot = true
+  config.vbguest.auto_update = true
 
   # Assume that the base box has the edx_ansible role installed
   # We can then tell the Vagrant instance to update itself.