[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/en-US/uploader.md

@@ -0,0 +1,45 @@
+## Uploader
+
+### Install
+``` javascript
+import { Uploader } from 'vant';
+
+Vue.component(Uploader.name, Uploader);
+```
+
+### Usage
+
+#### Basic Usage
+
+```html
+<div class="uploader-container">
+  <van-uploader :afterRead="logContent">
+    <van-icon name="photograph"></van-icon>
+  </van-uploader>
+</div>
+```
+
+```javascript
+export default {
+  methods: {
+    logContent(file) {
+      console.log(file)
+    }
+  }
+};
+```
+
+### API
+
+| Attribute | Description | Type | Default | Accepted Values |
+|-----------|-----------|-----------|-------------|-------------|
+| resultType | The way to read the file, read as base64; read as text | `String` | `dataUrl` | `text` |
+| disable | Whether to disable the upload, set to true during the image upload to prevent users from clicking this component to upload pictures | `Boolean` | `false` | - |
+| beforeRead | Hook before reading the file, the first parameter is the selected file, return false to stop reading the file | `Function` | - | - |
+| afterRead | Hook after reading the file, parameter format: { file ,content } | `Function` | - | - |
+
+### Slot
+
+| name | Description |
+|-----------|-----------|
+| - | Custom icon |