Add error message specifically for chef_server change

lib/vagrant/config/vm.rb

@@ -129,7 +129,12 @@ module Vagrant
 
         # Each provisioner can validate itself
         provisioners.each do |prov|
-          prov.validate(errors)
+          # TODO: Remove at some point
+          if prov.shortcut == :chef_server
+            errors.add(I18n.t("vagrant.config.vm.provisioner_chef_server_changed"))
+          else
+            prov.validate(errors)
+          end
         end
       end
     end

templates/locales/en.yml

@@ -173,6 +173,7 @@ en:
         box_missing: "A box must be specified."
         box_not_found: "The box '%{name}' could not be found."
         shared_folder_hostpath_missing: "Shared folder host path for '%{name}' doesn't exist: %{path}"
+        provisioner_chef_server_changed: "The provisioner 'chef_server' is now 'chef_client'"
         provisioner_not_found: "The provisioner '%{shortcut}' doesn't exist."
         provisioner_invalid_class: "The provisioner '%{shortcut}' must inherit from `Vagrant::Provisioners::Base`."