Update chromedriver to latest stable version

[shashidharus]

No description provided.

[stemount]

@atti187 The 2.3.1 chromedriver rectifies the need for Xvfb as per SeleniumHQ/docker-selenium#429. This PR looks good. 🏅

> [email protected] test /Users/stemount/projects/wdio-chromedriver-service
> npm run test:unit && npm run test:integration


> [email protected] test:unit /Users/stemount/projects/wdio-chromedriver-service
> mocha --compilers js:babel-register --recursive test/unit



  getFilePath
    ✓ should handle dir "./"
    ✓ should handle dir "./log"
    ✓ should handle dir "./log/"
    ✓ should handle dir "./log/chromedriver"
    ✓ should handle dir "log"
    ✓ should handle file ".log"
    ✓ should handle file "./.log"
    ✓ should handle file "./log/.log"
    ✓ should handle file "./chromedriver-log.txt"
    ✓ should handle file "chromedriver-log.txt"
    ✓ should handle file "./log/chromedriver-log.txt"
    ✓ should handle file "log/chromedriver-log.txt"


  12 passing (41ms)


> [email protected] test:integration /Users/stemount/projects/wdio-chromedriver-service
> wdio test/integration/wdio.conf.js


[14:20:42]  COMMAND	POST 	 "/session"
[14:20:42]  DATA		{"desiredCapabilities":{"javascriptEnabled":true,"locationContextEnabled":true,"handlesAlerts":true,"rotatable":true,"browserName":"chrome","loggingPrefs":{"browser":"ALL","driver":"ALL"},"requestOrigins":{"url":"http://webdriver.io","version":"4.6.2","name":"webdriverio"}}}
[14:20:43]  INFO	SET SESSION ID 0b73627d7baf54cf809f040109074ab7
[14:20:43]  RESULT		{"acceptSslCerts":true,"applicationCacheEnabled":false,"browserConnectionEnabled":false,"browserName":"chrome","chrome":{"chromedriverVersion":"2.32.498537 (cb2f855cbc7b82e20387eaf9a43f6b99b6105061)","userDataDir":"/var/folders/hg/fvhd1glx0hj9gs0lpwl2jrlr0000gn/T/.org.chromium.Chromium.S79pIt"},"cssSelectorsEnabled":true,"databaseEnabled":false,"handlesAlerts":true,"hasTouchScreen":false,"javascriptEnabled":true,"locationContextEnabled":true,"mobileEmulationEnabled":false,"nativeEvents":true,"networkConnectionEnabled":false,"pageLoadStrategy":"normal","platform":"Mac OS X","rotatable":false,"setWindowRect":true,"takesHeapSnapshot":true,"takesScreenshot":true,"unexpectedAlertBehaviour":"","version":"60.0.3112.113","webStorageEnabled":true}
[14:20:43]  COMMAND	POST 	 "/session/0b73627d7baf54cf809f040109074ab7/url"
[14:20:43]  DATA		{"url":"http://webdriver.io/"}
[14:20:47]  COMMAND	GET 	 "/session/0b73627d7baf54cf809f040109074ab7/title"
[14:20:47]  DATA		{}
[14:20:47]  RESULT		"WebdriverIO - WebDriver bindings for Node.js"
․․[14:20:47]  COMMAND	DELETE 	 "/session/0b73627d7baf54cf809f040109074ab7"
[14:20:47]  DATA		{}


2 passing (5.80s)```

[nao360]

Agree with @stemount - other than that, this PR looks great.