update readme badges to .svg

readme.md

@@ -1,9 +1,9 @@
 # Sprout
 
-[![npm](https://badge.fury.io/js/sprout.png)](http://badge.fury.io/js/sprout)
-[![tests](https://travis-ci.org/carrot/sprout.png?branch=master)](https://travis-ci.org/carrot/sprout)
-[![dependencies](https://david-dm.org/carrot/sprout.png?theme=shields.io)](https://david-dm.org/carrot/sprout)
-[![Coverage Status](https://coveralls.io/repos/carrot/sprout/badge.png?branch=cli-refactor)](https://coveralls.io/r/carrot/sprout?branch=cli-refactor)
+[![NPM version](https://badge.fury.io/js/sprout.svg)](http://badge.fury.io/js/sprout)
+[![tests](https://travis-ci.org/carrot/sprout.svg?branch=master)](https://travis-ci.org/carrot/sprout)
+[![Dependency Status](https://david-dm.org/carrot/sprout.svg)](https://david-dm.org/carrot/sprout)
+[![Coverage Status](http://img.shields.io/coveralls/carrot/sprout.svg)](https://coveralls.io/r/carrot/sprout?branch=master)
 
 Simple new project templating