Automatic light adjustment using the new DeviceLightEvent API.

Ref: https://dvcs.w3.org/hg/dap/raw-file/tip/light/Overview.html
Add image and style tasks for Gulp + watch/livereload in development
Move index.html into src/
Add boot.js and initial styles
Add gitignore file
Add EditorConfig file (http://editorconfig.org/)