title: Change the default error message with simple_form
body: <p>I don't manage to change the default error message from simple form, i tried to edit the simple form locale file but it seems to be ignored</p>
  
  <p>Here is my locale file :</p>
  
  <pre><code>#config/locales/simple_form.en.yml
  en:
    simple_form:
      error_notification:
        default_message: "A custom message:"
  </code></pre>
  
  <p>But i still get "Please review the problems below:"</p>
  
  <p>Does anybody knows what i'm doing wrong ?</p>