Introduce logging framework/library

The vanilla console.log/warn/error is convenient, and works on both client-side (browser) and server-side(e.g. nodejs) apps. But it only prints to stdout/stderr.

Popular logging frameworks like winston is powerful, providing different log levels, different format of output (stdout, a file, and a database etc.). But is not directly working on client-side so far, and introduce more dependencies.

A feasible solution is using a customized logger, and delegate logger.log to console.log or winston based on running environment.

該 issue 未指定任何檔案、測試或進入點。首先檢視針對 console 和 winston 提出的方案，包括它們在瀏覽器和 Node.js 中的行為；完成的標準是就一個支援所述環境和輸出選項的自訂 logger 設計達成共識。