Revert "remove required_field_name from ApplicationHelper"

This reverts commit a3896c6e2d.

app/helpers/application_helper.rb

@@ -66,6 +66,10 @@ module ApplicationHelper
     end
   end
 
+  def required_field_name(name = '')
+    safe_join [name, ' ', content_tag('span', '*', class: 'required')]
+  end
+
   def li_unless_nil(link)
     content_tag(:li, link) if link
   end