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!
Fwiw, this is the call with the race condition that causes infinite loops in shelljs.  We should probably add something to the readme indicating that if this script is taking forever, it should be killed and restarted.