Issue title: HELLO - Check your spelling - MacOS Driver
 Issue body: Your spelling is

`https://github.com/mozilla/geckodriver/releases/download/v0.10.0/geckodriver-v0.10.0-mac.tar.gz`

Which does not exist. Change it to:

https://github.com/mozilla/geckodriver/releases/download/v0.10.0/geckodriver-v0.10.0-macos.tar.gz
 Comments: 
 Comment 0: I have opened a issue on https://github.com/mozilla/geckodriver/issues/193
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