Readme: add Travis-CI badge

Readme.md

@@ -1,9 +1,12 @@
+# node-canvas
+## Canvas graphics API backed by Cairo
+
+[![Build Status](https://travis-ci.org/Automattic/node-canvas.svg?branch=master)](https://travis-ci.org/Automattic/node-canvas)
 [![NPM version](https://badge.fury.io/js/canvas.png)](http://badge.fury.io/js/canvas)
 [![Dependency Status](https://gemnasium.com/LearnBoost/node-canvas.png)](https://gemnasium.com/LearnBoost/node-canvas)
 
-# node-canvas
 
- Node canvas is a [Cairo](http://cairographics.org/) backed Canvas implementation for [NodeJS](http://nodejs.org).
+  node-canvas is a [Cairo](http://cairographics.org/) backed Canvas implementation for [NodeJS](http://nodejs.org).
 
 ## Authors