Don't attempt to render pages for Governments

This content is new to the Publishing API, and while I believe
Government Frontend is the appropriate place for it to be rendered, I
want to put of that decision, and the decisions around how to render
it until after the intended changes to history mode have been made, as
that's what I'm focusing on.

app/controllers/content_items_controller.rb

@@ -7,6 +7,7 @@ class ContentItemsController < ApplicationController
   rescue_from ActionController::UnknownFormat, with: :error_406
   rescue_from PresenterBuilder::RedirectRouteReturned, with: :error_redirect
   rescue_from PresenterBuilder::SpecialRouteReturned, with: :error_notfound
+  rescue_from PresenterBuilder::GovernmentReturned, with: :error_notfound
 
   attr_accessor :content_item, :taxonomy_navigation
 

app/services/presenter_builder.rb

@@ -9,6 +9,7 @@ def initialize(content_item, content_item_path)
   def presenter
     raise SpecialRouteReturned if special_route?
     raise RedirectRouteReturned, content_item if redirect_route?
+    raise GovernmentReturned if government_content_item?
 
     presenter_name.constantize.new(content_item, content_item_path)
   end
@@ -23,6 +24,10 @@ def redirect_route?
     content_item && content_item["schema_name"] == "redirect"
   end
 
+  def government_content_item?
+    content_item && content_item["document_type"] == "government"
+  end
+
   def presenter_name
     if service_sign_in_format?
       return service_sign_in_presenter_name
@@ -57,4 +62,5 @@ def initialize(content_item)
     end
   end
   class SpecialRouteReturned < StandardError; end
+  class GovernmentReturned < StandardError; end
 end