title: PayPal Request keep getting MALFORMED_REQUEST
body: <p>I tried to send a payment to PayPal. But for some reason I only get a MALFORMED_REQUEST error. 
  There are no more information. Not even with the getData() function for the exception.</p>
  
  <p>Here is the compiled JSON:</p>
  
  <pre><code>{
  "intent": "sale",
  "payer": {
      "payment_method": "paypal",
      "payer_info": {
          "first_name": "Testvorname",
          "last_name": "Testnachname",
          "email": "test@example.com",
          "suffix": "Herr"
      }
  },
  "transactions": [
      {
          "amount": {
              "currency": "EUR",
              "total": "72.00"
          },
          "item_list": {
              "items": [
                  {
                      "quantity": "4",
                      "name": "test1",
                      "price": "8",
                      "currency": "EUR"
                  },
                  {
                      "quantity": "2",
                      "name": "test2",
                      "price": "20",
                      "currency": "EUR"
                  }
              ]
          }
      }
  ],
  "redirect_urls": {
      "return_url": "https://www.google.de",
      "cancel_url": "https://www.google.de"
  } }
  </code></pre>
  
  <p>I have no Idea what could be wrong with this JSON.
  I'm using the PHP SDK.</p>