Webpack 2!

• Update to Babel 6
• Make CI build actually fail if Webpack build fails

• Updated all dependency versions
• Set up a travis build to make sure it keeps working across a few node versions
• Set up greenkeeper to keep dependencies up to date, and a david badge to show it off
• Replaced autoprefixer-loader with the autoprefixer + postcss-loader setup described here
• Made everything comply with standard