chromedriver kill fix

Fixes https://github.com/appium/appium/issues/3484 (also requires https://github.com/appium/appium/commit/921077a39d16b83a72dc12f6493a2cc155f98b6e)

@jlipps can you check looks like the both ChromeDriver kill methods were broken, and didLaunch wasn't set for Chrome case triggering errors down the line.