title: result.credit_card_verification is returning nil even on error in braintree
body: <p>I'm using braintree for payment processing and I'm trying to get <a href="https://www.braintreepayments.com/docs/ruby/reference/processor_responses" rel="nofollow">Processor Response Codes</a> from Braintree with Ruby. </p>
  
  <p>Here is my code :</p>
  
  <pre><code> verification = result.credit_card_verification
   response_code = verification.try(:processor_response_code)
  </code></pre>
  
  <p>I'm getting verification as nil even when there is error.</p>
  
  <p>Is there something else to get Processor Response Codes?</p>
  
  <p>I got this code from <a href="https://www.braintreepayments.com/docs/ruby/card_verifications/overview" rel="nofollow">here</a></p>
  
  <p>Here is my result.erros : </p>
  
  <pre><code>:errors: !ruby/object:Braintree::Errors
    errors: !ruby/object:Braintree::ValidationErrorCollection
      errors: []
      nested:
        :customer: !ruby/object:Braintree::ValidationErrorCollection
          errors: []
          nested:
            :credit_card: !ruby/object:Braintree::ValidationErrorCollection
              errors:
              - !ruby/object:Braintree::ValidationError
                code: '81707'
                attribute: cvv
                message: CVV must be 4 digits for American Express and 3 digits for
                  other card types.
              - !ruby/object:Braintree::ValidationError
                code: '81713'
                attribute: expiration_year
                message: Expiration year is invalid.
              - !ruby/object:Braintree::ValidationError
                code: '81703'
                attribute: number
                message: Credit card type is not accepted by this merchant account.
              - !ruby/object:Braintree::ValidationError
                code: '81715'
                attribute: number
                message: Credit card number is invalid.
              nested:
                :billing_address: !ruby/object:Braintree::ValidationErrorCollection
                  errors: []
                  nested: {}
  </code></pre>