Execute test scripts in incognito mode

[Sjain01]

@john-doherty - First of all thank you for this amazing library.

Although I had already asked this question via https://github.com/john-doherty/selenium-cucumber-js/issues/76 since the suggestion in there is not working and I cannot re-open it, I opened a new issue.

As per the suggestion, adding incognito under runtime folder in chromeDriver.js is not working.

` 'use strict';

var chromedriver = require('chromedriver'); var selenium = require('selenium-webdriver');

/**

• Creates a Selenium WebDriver using Chrome as the browser

• @returns {ThenableWebDriver} selenium web driver */ module.exports = function() {

  var driver = new selenium.Builder().withCapabilities({ browserName: 'chrome', javascriptEnabled: true, acceptSslCerts: true, chromeOptions: { args: ['start-maximized', 'disable-extensions','incognito'] }, path: chromedriver.path }).build();

  driver.manage().window().maximize();

  return driver; };`