This patch:
- reformats codebase to use 2-spaces instead of 4. This will
align the project with other codebases (e.g. DevTools and Lighthouse)
- enables eslint indentation checking
References #19
This patch introduces check_availability.js utility which looks for
available chromium binaries for different revisions and platforms.
This patch also re-factors the chromium downloader scripts so that
it can operate different platforms.
