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!
So, if I understand this correctly, there are two `main.js` files, one for dev and one for production.  You have the comment in here because if you were to look at `main.js` and wonder what the difference is between the files, you would notice that `window.config` is not specified here and that's why you have the comment?

What things need to be kept in sync between the "prod" set of files and the "non-prod" set of files?