Update README.md, CONTRIBUTING.md

Update CONTRIBUTING.md

Merge PR#272: Make explicit dependency to babel-core

Merge pull request #238 from MyBoon/patch-1

Use global.WATCH instead of global.watch

Update npm modules

Fix #83: Externals setting for server-side bundle in webpack.config.js

...also update browser-sync 2.5.2 > 2.5.3 and less 2.4.0 > 2.5.0

Add style-loader to client-side bundling configuration. Fixes #72

Update webpack.config.js

  - Add `url-loader` for `.svg` files
  - Fix `jest` preprocessor setting in `package.json`