Update travis badge

Author: davidnguyen11

README.md

@@ -1,6 +1,6 @@
 # React Is In Viewport
 
-[![codecov](https://codecov.io/gh/davidnguyen179/react-is-in-viewport/branch/master/graph/badge.svg)](https://codecov.io/gh/davidnguyen179/react-is-in-viewport) [![Build Status](https://travis-ci.com/davidnguyen179/viewport.svg?branch=master)](https://travis-ci.com/davidnguyen179/viewport) [![Greenkeeper badge](https://badges.greenkeeper.io/davidnguyen179/react-is-in-viewport.svg)](https://greenkeeper.io/)
+[![codecov](https://codecov.io/gh/davidnguyen179/react-is-in-viewport/branch/master/graph/badge.svg)](https://codecov.io/gh/davidnguyen179/react-is-in-viewport) [![Build Status](https://travis-ci.com/davidnguyen179/react-is-in-viewport.svg?branch=master)](https://travis-ci.com/davidnguyen179/react-is-in-viewport) [![Greenkeeper badge](https://badges.greenkeeper.io/davidnguyen179/react-is-in-viewport.svg)](https://greenkeeper.io/) [![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/davidnguyen179/react-is-in-viewport/blob/master/LICENSE) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square)](http://makeapullrequest.com)
 
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