Added .gitattributes file to (hopefully) solve CRLF/LF issues regardless of local settings.
This file needs to be kept up-to-date with any new file extensions that appear in the repo.
More info: https://help.github.com/articles/dealing-with-line-endings/#refreshing-a-repository-after-changing-line-endings

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>