Upgrade react router 4 - #5

@moshie Thanks for making the new pull request.

I noticed that some areas that have been refactored to ES6 class and import/export have been undone/reverted. Do you mind amending your commits so that the ES6 changes are kept?

And could you also make a few styling tweaks:

• End each file with a newline (follow the Unix EOL convention)
• Capitalize component filename (rename views/app.jsx to views/App.jsx)

Once again, much appreciated for the time and effort on this.

@remarkablemark No worries

I have made the changes you requested.

Babel wraps the es6 components in an object making them only accessible from the default property which is the reason for this var App = require('../views/App.jsx').default; in client.js & routes/index.jsx.

Hope this is ok this is the only way I could get this to work without mixing es6 & es5.

@moshie Thanks for the update. I'll continue the ES6 refactor in a future commit.