Server-side routing improvement: request.rawBody

Allows access to a property `rawBody` on `this.request` for server routes. Added this feature as an express middleware.

Note that this addition may be unnecessary... connect.bodyParser() should have done the trick, but I was not able to get it to parse POST requests automatically (these were originating from AWS SNS).

I instead rely on doing `JSON.parse(this.request.rawBody)`.