Move build-time npm packages to devDependencies

[ahoym]

Fixes: #33

I don't think this breaks any of the existing scripts, but it would probably be a good idea to double check.

The Context

The only run-time packages that the src/index.js file uses is 'react' and 'lodash.debounce'. Everything else can be installed as a devDependency.

Moving build-time packages like webpack, *-loaders, and babel-* helps reduce the cruft for users that want to npm shrinkwrap.

This PR

• Moves the following packages from dependencies to devDependencies
  • autoprefixer-core
  • babel
  • babel-core
  • babel-jest
  • babel-loader
  • css-loader
  • csswring
  • extract-text-webpack-plugin
  • file-loader
  • gh-pages-deploy
  • jsx-loader
  • normalize.css
  • postcss-loader
  • root-require
  • sass-loader
  • script-loader
  • style-loader
  • url-loader
  • webpack
  • webpack-dev-server

[seethroughdev]

Thanks for doing this @ahoym . That's definitely how it should be.