Migrate off of brfs to a webpack loader which supports sourcemaps

If you import react-canvas and compile it using webpack you'll lose any hope of having sourcemaps to go along with your work due to [brfs not supporting it](https://github.com/substack/brfs/issues/7). I'm fairly new to this code base but it doesn't like you are doing anything that you need transform-loader for. This is a pretty big dependency and with a little guidance, I'd be happy to try and pull it out.