Adds middleware to the same Layer as the renderer

[felkerch]

Amphora currently attaches route-specific middleware by adding two Layers to the router: one for the middleware and then one for the renderer. This PR adds them to the same layer. Basically this is the diff:

- router.use(path, middleware);
- router.get(path, renderer);
+ router.get(path, [middleware, renderer]);

You'll see different behavior if your middleware makes changes to the request (we change the URL for pagination).

The interface for adding routes to a site remains the same:

module.exports.routes = [
    { path: "/:name", middleware: [fn] },
    ...
]

[coveralls]

Pull Request Test Coverage Report for Build 2428

• 20 of 20 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 2426:	0.0%
Covered Lines:	4178
Relevant Lines:	4178

---

💛 - Coveralls