Upgrade versions

[brianium]

In light of the recent PR, I was doing a little code review and noticed the pinned versions of standalone and the drivers are lagging behind a bit.

Might be nice to update all those versions to the latest and greatest.

[hackel]

Not only are they lagging behind, chromedriver 2.19 flat-out doesn't function anymore. If there isn't a way to automatically detect the latest version, there should be a way to specify a custom version/URL. I've switched to angular/webdriver-manager for now.