Refactor to Webpack Build

This was a big release:

• refactored the build to webpack, so dropped gulp
• updated to react 0.13
• moved client/src to app
• added iojs to build targets

Refactor as a Single Pager

This is one of the biggest release so far. This includes a lot of refactor so that the application uses a real authentication flow, from the auth store and becomes a single pager (even for login). The server now has a single page to render and then everything is handle by react-router.