Fix pay now button

not sure if the action parameter in order creation request affects anything, but the docs say that it should match the js sdk commit parameter

tests/PHPUnit/Button/Endpoint/CreateOrderEndpointTest.php

@@ -167,6 +167,7 @@ class CreateOrderEndpointTest extends TestCase
 			false,
 			CardBillingMode::MINIMAL_INPUT,
 			false,
+			['checkout'],
 			new NullLogger()
         );
         return array($payer_factory, $testee);