update readme

Author: REBOOTERS

README.md

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 ![Image](/image/banner.png)
 
 # Matisse
-[![Build Status](https://travis-ci.org/zhihu/Matisse.svg)](https://travis-ci.org/zhihu/Matisse) [ ![Download](https://api.bintray.com/packages/zhihu/maven/matisse/images/download.svg?version=0.5.1-beta1) ](https://bintray.com/zhihu/maven/matisse/0.5.1-beta1/link)
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+[![Build Status](https://travis-ci.org/zhihu/Matisse.svg)](https://travis-ci.org/zhihu/Matisse) [ ![Download](https://api.bintray.com/packages/zhihu/maven/matisse/images/download.svg) ](https://bintray.com/zhihu/maven/matisse/_latestVersion)
 Matisse is a well-designed local image and video selector for Android. You can  
 - Use it in Activity or Fragment
 - Select images including JPEG, PNG, GIF and videos including MPEG, MP4