add suppliers/lists ui styling and security fixes

app/helpers/application_helper.rb

@@ -14,6 +14,12 @@ module ApplicationHelper
     end
   end
 
+  # overwrite i18n l, to handle nil values
+  def l(*args)
+    return '' unless args.first
+    super(*args)
+  end
+
   def are_you_sure?
     t('helpers.links.are_you_sure')
   end
@@ -57,4 +63,8 @@ module ApplicationHelper
   def slider_image
     image_tag('spinner.gif')
   end
+
+  def show_boolean(bool)
+    t("general.boolean.boolean_#{bool.present? ? 'yes' : 'no'}")
+  end
 end