chore(readme): use svg status shield for Travis (#3706)

Author: cnishina

README.md

@@ -1,4 +1,4 @@
-Protractor [![Build Status](https://travis-ci.org/angular/protractor.png?branch=master)](https://travis-ci.org/angular/protractor) [![CircleCI Status](https://circleci.com/gh/angular/protractor.svg?style=shield)](https://circleci.com/gh/angular/protractor) [![Join the chat at https://gitter.im/angular/protractor](https://badges.gitter.im/angular/protractor.svg)](https://gitter.im/angular/protractor)
+Protractor [![Build Status](https://travis-ci.org/angular/protractor.svg?branch=master)](https://travis-ci.org/angular/protractor) [![CircleCI Status](https://circleci.com/gh/angular/protractor.svg?style=shield)](https://circleci.com/gh/angular/protractor) [![Join the chat at https://gitter.im/angular/protractor](https://badges.gitter.im/angular/protractor.svg)](https://gitter.im/angular/protractor)
 ==========
 
 [Protractor](http://angular.github.io/protractor) is an end-to-end test framework for [AngularJS](http://angularjs.org/) applications. Protractor is a [Node.js](http://nodejs.org/) program built on top of [WebDriverJS](https://github.com/SeleniumHQ/selenium/wiki/WebDriverJs). Protractor runs tests against your application running in a real browser, interacting with it as a user would.