Added server.js file to root so that Azure will build properly on deploy

When deploying Ghost to Azure the build fails because Azure expects there to be a server.js (or app.js) file in the Express app root. This small change allows Azure to build the site properly on first deploy.

In addition (sorry I meant to put this into another PR) I added a route for historical Wordpress-style URLs. This simply allows for their presence and routes to the slugged post - this is nice for backwards compatibility of imported blogs (like mine).