def start_payment(reservation_key)
      path = "reservation/#{reservation_key}/payment"
      result = call(path, http_method: :post)
      if result.code.to_i == 200
        return true
      else
        raise ShakeTheCounterError.new "Payment failed"
      end
    end
def start_payment(reservation_key)
      path = "reservation/#{reservation_key}/payment"
      result = call(path, http_method: :post)
      if result.code.to_i == 200
        return true
      else
        raise ShakeTheCounterError.new "Payment failed"
      end
    end
Send a message to STC that a payment
 has started.

 @return String status