Ensure the app is always last in the middleware stack.

By ensuring the app is always bound after the event, event listeners can
be less careful. Without this plugins would always have to use
insertBefore() which is kind of awkward.

src/Http/Server.php

@@ -77,8 +77,8 @@ class Server
         if (!($middleware instanceof MiddlewareStack)) {
             throw new RuntimeException('The application `middleware` method did not return a middleware stack.');
         }
-        $middleware->push($this->app);
         $this->dispatchEvent('Server.buildMiddleware', ['middleware' => $middleware]);
+        $middleware->push($this->app);
         $response = $this->runner->run($middleware, $request, $response);
 
         if (!($response instanceof ResponseInterface)) {

tests/TestCase/Http/ServerTest.php

@@ -179,12 +179,19 @@ class ServerTest extends TestCase
     {
         $app = new MiddlewareApplication($this->config);
         $server = new Server($app);
-        $called = false;
-        $server->eventManager()->on('Server.buildMiddleware', function ($event, $middleware) use (&$called) {
-            $called = true;
+        $this->called = false;
+
+        $server->eventManager()->on('Server.buildMiddleware', function ($event, $middleware) {
             $this->assertInstanceOf('Cake\Http\MiddlewareStack', $middleware);
+            $middleware->push(function ($req, $res, $next) {
+                $this->called = true;
+                return $next($req, $res);
+            });
+            $this->middleware = $middleware;
         });
         $server->run();
-        $this->assertTrue($called, 'Event not triggered.');
+        $this->assertTrue($this->called, 'Middleware added in the event was not triggered.');
+        $this->assertInstanceOf('Closure', $this->middleware->get(3), '2nd last middleware is a clousure');
+        $this->assertSame($app, $this->middleware->get(4), 'Last middleware is an app instance');
     }
 }