Add site setting to disable User Directory, include restricted info

spec/controllers/directory_items_controller_spec.rb

@@ -11,6 +11,7 @@ describe DirectoryItemsController do
     response.should_not be_success
   end
 
+
   context "without data" do
 
     context "and a logged in user" do
@@ -42,5 +43,12 @@ describe DirectoryItemsController do
       json['total_rows_directory_items'].should be_present
       json['load_more_directory_items'].should be_present
     end
+
+    it "fails when the directory is disabled" do
+      SiteSetting.enable_user_directory = false
+
+      xhr :get, :index, period: 'all'
+      response.should_not be_success
+    end
   end
 end