title: Braintree Drop-In UI does not show CVV field
body: <p>I'm fairly new to Braintree API. I'm using Recurring Payments. And for that I'm using Drop-In UI that is provided by Braintree. Everything goes well but it only shows two fields: Card Number and Expiration Month/Year; and the Paypal button. It's not showing CVV field.</p>
  
  <p>I believe the CVV field is optional and the transaction will still go through if I were to not accept it. But I'm wondering why is it not showing up?</p>
  
  <p>Braintree's new documentation is very limited. And I can't find much info on this problem their website. Any pointers will be much appreciated. Thanks.</p>