[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/progress.md

@@ -0,0 +1,49 @@
+## Progress
+
+### Install
+``` javascript
+import { Progress } from 'vant';
+
+Vue.component(Progress.name, Progress);
+```
+
+### Usage
+
+#### Basic Usage
+Use 'percentage' prop to set current progress
+
+```html
+<van-progress :percentage="0" />
+<van-progress :percentage="46" />
+<van-progress :percentage="100" />
+```
+
+
+#### Inactive
+
+```html
+<van-progress inactive :percentage="0" />
+<van-progress inactive :percentage="46" />
+<van-progress inactive :percentage="100" />
+```
+
+
+#### Custom Style
+Use `pivotText` to custom text，use `color` to custom bar color
+
+```html
+<van-progress pivotText="Red" color="#ed5050" :percentage="26" />
+<van-progress pivotText="Orange" color="#f60" :percentage="46" />
+<van-progress pivotText="Yellow" color="#f09000" :percentage="66" />
+```
+
+### API
+
+| Attribute | Description | Type | Default | Accepted Values |
+|-----------|-----------|-----------|-------------|-------------|
+| inactive | Whether to be gray | `Boolean` | `false` | - |
+| percentage | Percentage | `Number` | `false` | `0-100` |
+| showPivot | Whether to show text | `Boolean` | `true` | - |
+| pivotText | Text | `String` | percentage | - |
+| color | Color | `String` | `#38f` | hexvalue |
+| textColor | Text color | `String` | `#fff` | hexvalue |