add build status badge as markdown

Author: normansander

README.md

@@ -1,7 +1,4 @@
-<p>
-  <a href="https://travis-ci.org/KitchenStories/vue-gallery-slideshow"><img src="https://img.shields.io/travis/KitchenStories/vue-gallery-slideshow.svg?style=flat-square"></a>
-  <a href="https://www.npmjs.com/package/vue-gallery-slideshow"><img src="https://img.shields.io/npm/dt/vue-gallery-slideshow.svg?style=flat-square"></a>
-</p>  
+[![Build Status](https://travis-ci.org/KitchenStories/vue-gallery-slideshow.svg?branch=master)](https://travis-ci.org/KitchenStories/vue-gallery-slideshow)
 
 # vue-gallery-slideshow