@beamjet Check Mac Value generation

Re: http://www.allpay.com.tw/Content/files/AllPay%E5%85%A8%E5%8A%9F%E8%83%BD%E9%87%91%E6%B5%81%E6%95%B4%E5%90%88%E4%BB%8B%E6%8E%A5%E8%A6%8F%E6%A0%BC%E8%AA%AA%E6%98%8E.pdf  11. 檢查碼機制

Added very basic unit testing. Thanks!