Use vagrant-vbguest plugin to sync VirtualBox Guest Editions versions

Wiki will need to be updated to reflect this addition

Added script to auto install vagrant-vbguest if it's needed

vagrant/release/devstack/Vagrantfile

@@ -61,6 +61,16 @@ 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
+  if !Vagrant.has_plugin?('vagrant-vbguest') && ENV['SKIP'] != 'true'
+    print "Installing vagrant plugin vagrant-vbguest..."
+    %x(bash -c "export SKIP=true; vagrant plugin install vagrant-vbguest") unless Vagrant.has_plugin?('vagrant-vbguest') || ENV['SKIP'] == 'true'
+    puts "Done!"
+    puts "Please re-run your vagrant command again..."
+    exit
+  end
+  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.