Update dependencies and readme

- Update Ruby (Jekyll, s3_website deploy tool) dependencies
- Update Node (Grunt build process) dependencies
- Update Bower (client-side JS) dependencies
- Add Install, Development, and Deployment instructions to README
- Switch from `jekyll-s3` to `s3_website` as deploy tool
- Switch from `grunt-browserify2` to `grunt-browserify`
- Remove `redcarpet` dependency (included in `jekyll`)