README.md

showBigPicture查看大图 插件形式调用

```html
      <h-button class="button-class" type="primary" @click.native="showBigPicture">showBigPicture</h-button>

      showBigPicture() {
        hlsPopup.showBigPicture({
          imgUrl: 'http://hlsapp.hand-china.com/hls_file/2018/05/F1B6D85E409A4714A8540504B2D133AD'
        })
      },
      
      let list = [{imgUrl:'base64'},{imgUrl:'http://XXX'}]      
      showBigPicture() {
         ShowPicturePlugin.show({
            imgList: list,
            startPosition: 1,
         })
      },
                
```