FEATURE: allow for a localized error when a regex fails in site settings

FEATURE: apply string validation to list site settings (so we get regex)

spec/models/site_setting_spec.rb

@@ -63,7 +63,7 @@ describe SiteSetting do
   end
 
   describe "top_menu" do
-    before(:each) { SiteSetting.top_menu = 'one,-nope|two|three,-not|four,ignored|category/xyz' }
+    before { SiteSetting.top_menu = 'one,-nope|two|three,-not|four,ignored|category/xyz|latest' }
 
     describe "items" do
       let(:items) { SiteSetting.top_menu_items }