[new feature] add i18n support (#310)

* fix: Tabbar icon line-height

* [new feature] progress add showPivot prop

* [new feature] TabItem support vue-router

* [new feature] update document header style

* [Doc] add toast english ducoment

* [new feature] add i18n support

* feat: Extract demos from markdown

* feat: Base components demos

* [new feature] complete demo extract & translate

* [fix] text cases

* fix: add deepAssign test cases

* fix: changelog detail

* [new feature] AddressEdit support i18n

docs/markdown/zh-CN/popup.md

@@ -0,0 +1,48 @@
+## Popup 弹出层
+
+### 使用指南
+``` javascript
+import { Popup } from 'vant';
+
+Vue.component(Popup.name, Popup);
+```
+
+### 代码演示
+
+#### 基础用法
+`popup`默认从中间弹出
+
+```html
+<van-popup v-model="show">内容</van-popup>
+```
+
+```javascript
+export default {
+  data() {
+    return {
+      show: false
+    }
+  }
+};
+```
+
+#### 弹出位置
+通过`position`属性设置 Popup 弹出位置
+
+```html
+<van-popup v-model="show" position="top" :overlay="false">
+  内容
+</van-popup>
+```
+
+### API
+
+| 参数 | 说明 | 类型 | 默认值 | 可选值 |
+|-----------|-----------|-----------|-------------|-------------|
+| v-model | 当前组件是否显示 | `Boolean` | `false` | - |
+| overlay | 是否显示背景遮罩层 | `Boolean` | `true` | - |
+| lockOnScroll | 背景是否跟随滚动 | `Boolean` | `false` | - |
+| position | 弹出层位置 | `String` | - | `top` `bottom` `right` `left` |
+| closeOnClickOverlay | 点击遮罩层是否关闭弹出层 | `Boolean` | `true` | - |
+| transition | 弹出层的`transition` | `String` | `popup-slide` | - |
+| preventScroll | 是否防止滚动穿透 | `Boolean` | `false` | - |