emoji commits

From https://github.com/atom/atom/blob/master/CONTRIBUTING.md#git-commit-messages

• Consider starting the commit message with an applicable emoji: * 🎨 :art: when improving the format/structure of the code * 🐎 :racehorse: when improving performance * 🚱 :non-potable_water: when plugging memory leaks * 📝 :memo: when writing docs * 🐧 :penguin: when fixing something on Linux * 🍎 :apple: when fixing something on Mac OS * 🏁 :checkered_flag: when fixing something on Windows * 🐛 :bug: when fixing a bug * 🔥 :fire: when removing code or files * 💚 :green_heart: when fixing the CI build * ✅ :white_check_mark: when adding tests * 🔒 :lock: when dealing with security * ⬆️ :arrow_up: when upgrading dependencies * ⬇️ :arrow_down: when downgrading dependencies * 👕 :shirt: when removing linter warnings