rename Countdown to CountDown

src/components/CountDown/demo/simple.md

+---
+order: 0
+title: Simple
+---
+
+简单的页头。
+
+````jsx
+import CountDown from 'ant-design-pro/lib/CountDown';
+
+const targetTime = new Date().getTime() + 3900000;
+
+ReactDOM.render(
+  <CountDown target={targetTime} />
+, mountNode);
+````

src/components/CountDown/index.js

+import React, { Component } from 'react';
+
+function fixedZero(val) {
+  return val * 1 < 10 ? `0${val}` : val;
+}
+
+class CountDown extends Component {
+  constructor(props) {
+    super(props);
+
+    const { lastTime } = this.initTime(props);
+
+    this.state = {
+      lastTime,
+    };
+  }
+
+  componentDidMount() {
+    this.tick();
+  }
+
+  componentWillReceiveProps(nextProps) {
+    if (this.props.target !== nextProps.target) {
+      const { lastTime } = this.initTime(nextProps);
+      this.setState({
+        lastTime,
+      });
+    }
+  }
+
+  componentWillUnmount() {
+    clearTimeout(this.timer);
+  }
+
+  timer = 0;
+  interval = 1000;
+  initTime = (props) => {
+    let lastTime = 0;
+    let targetTime = 0;
+    try {
+      if (Object.prototype.toString.call(props.target) === '[object Date]') {
+        targetTime = props.target.getTime();
+      } else {
+        targetTime = new Date(props.target).getTime();
+      }
+    } catch (e) {
+      throw new Error('invalid target prop', e);
+    }
+
+    lastTime = targetTime - new Date().getTime();
+
+    return {
+      lastTime,
+    };
+  }
+  // defaultFormat = time => (
+  //  <span>{moment(time).format('hh:mm:ss')}</span>
+  // );
+  defaultFormat = (time) => {
+    const hours = 60 * 60 * 1000;
+    const minutes = 60 * 1000;
+
+    const h = fixedZero(Math.floor(time / hours));
+    const m = fixedZero(Math.floor((time - (h * hours)) / minutes));
+    const s = fixedZero(Math.floor((time - (h * hours) - (m * minutes)) / 1000));
+    return (
+      <span>{h}:{m}:{s}</span>
+    );
+  }
+  tick = () => {
+    const { onEnd } = this.props;
+    let { lastTime } = this.state;
+
+    this.timer = setTimeout(() => {
+      if (lastTime < this.interval) {
+        clearTimeout(this.timer);
+        this.setState({
+          lastTime: 0,
+        });
+
+        if (onEnd) {
+          onEnd();
+        }
+      } else {
+        lastTime -= this.interval;
+        this.setState({
+          lastTime,
+        });
+
+        this.tick();
+      }
+    }, this.interval);
+  }
+
+  render() {
+    const { format = this.defaultFormat } = this.props;
+    const { lastTime } = this.state;
+
+    const result = format(lastTime);
+
+    return result;
+  }
+}
+
+export default CountDown;

src/components/CountDown/index.md

+---
+category: Components
+type: General
+title: CountDown 
+subtitle: 倒计时
+cols: 1
+---
+
+倒计时组件。
+
+## API
+
+| 参数      | 说明                                      | 类型         | 默认值 |
+|----------|------------------------------------------|-------------|-------|
+| format | 时间格式化显示显示 | Function(time) |  |
+| target | 目标时间 | Date | - |