Remove broken Travis badge (#612)

Author: cbala-stripe

README.md

@@ -3,7 +3,6 @@
 React components for
 [Stripe.js and Elements](https://stripe.com/docs/stripe-js).
 
-[![build status](https://img.shields.io/travis/stripe/react-stripe-js/master.svg?style=flat-square)](https://travis-ci.org/stripe/react-stripe-js)
 [![npm version](https://img.shields.io/npm/v/@stripe/react-stripe-js.svg?style=flat-square)](https://www.npmjs.com/package/@stripe/react-stripe-js)
 
 ## Requirements