Added react-router, setup a blank groups page

Okay so I added react-router so we can switch pages quickly. Basically the application now begins at router.jsx. Router.jsx will render something like this: 

```
<div id="container">
 <Navbar />
 <Sidebar />
 <RouteHandler />
</div>
```

Basically then RouteHandler will determine what page is being displayed within the container. Default will be the Main panel. 

I also fixed a little bit of CSS and added two links, one for home ("/" route) and one for a placeholder groups page ("/groups" route). 

Getting react-router setup with RequireJS was kind of tricky (required doing a shim and it's still a little ugly because react-router uses global namespace). Let me know if you've got any questions. 

-Francis