Fix travis ci badge link

Author: jamesls

README.md

@@ -1,6 +1,6 @@
 # jmespath.js
 
-[![Build Status](https://travis-ci.org/jmespath/jmespath.js?branch=master)](https://travis-ci.org/jmespath/jmespath.js)
+[![Build Status](https://travis-ci.org/jmespath/jmespath.js.png?branch=master)](https://travis-ci.org/jmespath/jmespath.js)
 
 jmespath.js is a javascript implementation of JMESPath,
 which is a query language for JSON.  It will take a JSON