fix(launcher): ignore asynchronous code in afterLaunch

See #1413
docs(phantomjs): fix broken suggested configuration for PhantomJS and add a warning note
fix(launcher): allow afterLaunch to run async scripts
feat(runner): add a new method of getting browser drivers - directConnect

directConnect as an option on the configuration will replace chromeOnly.
Now, WebDriverJS allows Firefox to be used directly as well, so directConnect
will work for Chrome and Firefox, and throw an error if another browser is used.

This change deprecates but does not remove the chromeOnly option.