title: reCaptcha: allow for all domains or add via API
body: <p>I'm using the new reCaptcha from Google (with the checkbox and NOT the one with the text to rewrite).
  As I'm hosting multiple domains (a lot), I can't add all the domains in the admin panel.</p>
  
  <p><strong>My question</strong> :</p>
  
  <ul>
  <li>is it possible to allow the captcha for <strong>all the domains</strong> ?</li>
  <li>is there a way (API ?) to <strong>add new domain</strong> to my list ?</li>
  </ul>
  
  <p>If not, can you recommand me an alternative for this reCaptcha that allows per default all the domains ?</p>
  
  <p>Thanks a lot in advance</p>