Switch to webpack workflow

A set of changes to match Blip and Clamshell's front-end workflow with Webpack.

@cheddar Do you want to take a look and tell me what you think? Thanks!
After giving this a bit more thought, there is more going on than just the fact that it watches files or not (in `NODE_ENV=production`, we actually server the `dist/` directory, vs. in `NODE_ENV=development`, we "serve" de source files directly, bundling them on the fly).

This usage of `NODE_ENV` is pretty standard in Node community I think, so unless you still have strong feelings against it, I would like to keep it? What do you think?