refund spec

spec/fixtures/refund_response.json

@@ -0,0 +1,11 @@
+{
+  "id": "2491ab0c-0015-5000-9000-1640c7f1a6f0",
+  "status": "succeeded",
+  "amount": {
+    "value": "8.00",
+    "currency": "RUB"
+  },
+  "created_at": "2019-06-11T11:58:04.502Z",
+  "description": "test refund, idem-key 78c95366-ec4b-4284-a0fd-41e694bcdf11",
+  "payment_id": "2491a6e2-000f-5000-9000-1480e820ae17"
+}