download chromedriver from mirror website

When run web auto test with Selenium, the chromedriver is needed when the target browser is chrome.

Unfortunately,  the chromedriver is developed by google and google is blocked by the China Great Wall.

So we need figure out some other ways to download the chromedriver.

Fortunately, below sites can download the chromedriver,

https://npm.taobao.org/mirrors/chromedriver

淘宝 NPM 镜像

这是一个完整 npmjs.org 镜像，你可以用此代替官方版本(只读)，同步频率目前为 10分钟 一次以保证尽量与官方服务同步。

• 当前 registry.npm.taobao.org 是从 r.cnpmjs.org 进行全量同步的.
• 当前 npm.taobao.org 运行版本是: cnpmjs.org@3.0.0-alpha.8
• 本系统运行在 Node.js@v6.10.2 上.
• 开源镜像: http://npm.taobao.org/mirrors
• Node.js 镜像: http://npm.taobao.org/mirrors/node
• alinode 镜像: http://npm.taobao.org/mirrors/alinode
• phantomjs 镜像: http://npm.taobao.org/mirrors/phantomjs
• ChromeDriver 镜像: http://npm.taobao.org/mirrors/chromedriver
• OperaDriver 镜像: http://npm.taobao.org/mirrors/operadriver
• Selenium 镜像: http://npm.taobao.org/mirrors/selenium
• Node.js 文档镜像: http://npm.taobao.org/mirrors/node/latest/docs/api/index.html
• NPM 镜像: https://npm.taobao.org/mirrors/npm/
• electron 镜像: https://npm.taobao.org/mirrors/electron/
• node-inspector 镜像: https://npm.taobao.org/mirrors/node-inspector/