Faster development builds using webpack-dev-server

[spirulence]

@caryoscelus when you have a chance, please test and let me know if these changes help you.

I've changed the npm run names, it's now:

"scripts": {
    "clean": "rimraf dist",
    "assets": "npm run clean && mkdirp dist && ncp assets dist/assets",
    "build": "npm run assets && webpack -p",
    "develop": "webpack-dev-server",
    "develop-no-server": "npm run assets && webpack"
  },

You'll likely need to npm install again as some new dependencies have been added.

[spirulence]

Comes with the added bonus that you don't need to build for a simple asset change.

[spirulence]

This is really handy, and as it preserves existing functionality, I'm going to go ahead and merge it.

[caryoscelus]

Yeah, works great!