Create an order/cart

Example request

{
  "external_id": "my_order_123",
  "contact_id": "jdoe@email.com",
  "card_code": "my_card_code",
  "store_external_id": "ext_madeleine",
  "ordered_at": "2018-01-12 15:00:00",
  "discount_amount": 0.25,
  "shipping_amount": 0.75,
  "total_price": 1.55,
  "tax_amount": 0.55,
  "sales_person": "John Doe",
  "currency": "EUR",
  "products": [
    {
      "product_id": "10",
      "unit_price": "25",
      "quantity": 2,
      "discount_amount": 0,
      "tax_amount": 0,
      "currency": "EUR",
      "total_line_amount": "50"
    }
  ],
  "custom_fields": [
    {
      "name": "foo",
      "value": "bar"
    },
    {
      "name": "foo2",
      "value": "bar2"
    }
  ]
}