Add action to copy chromedriver.
Create dist for chromedriver and upload it.
default_app: Don't quit when started as web driver.
Make our user agent string follow standard.
Pretend to be Chrome by default.

This is used to cheat client web drivers.
docs: Document how to use chromedriver.
docs: use => using
Merge pull request #652 from atom/chromedriver

Ship chromedriver and add docs on how to use it
win: Add "direct-write" option for BrowserWindow.

For atom/atom#3540.
Merge pull request #655 from hokein/master

SetProgressBar API Implementation, fixes #635
Only include chromedriver in vX.X.0 releases.
Fix chromedriver's version in archive.
Bump v0.16.3.
Fix creating empty chromedriver archive.
mac: Fix dock progress bar doesn't show after hiding, fixes #658.