Misc. Fixes

- Fetches latest master.
- Added sample.css to .gitignore.
- Appveyor is now fixed. Tests are running. /cc @kevva, @deepak1556  :)
- Change behavior of how source-comments work. Its a breaking change. `sourceComments` is now treated as bool from CLI as well as the code.
This looks to me as though you've undone the changes @kevva made in #484. You might need to just correct that.