Removed 'before'/'after'

example/dartlang_org.dart

@@ -19,7 +19,7 @@ main() async {
   });
 
   // Proxy any other request through to dartlang.org
-  app.after.add(angelHandler);
+  app.use(angelHandler);
 
   var server = await app.startServer(InternetAddress.LOOPBACK_IP_V4, 8080);
   print('Proxying at http://${server.address.host}:${server.port}');

lib/src/support_shelf.dart

@@ -12,7 +12,7 @@ import 'convert.dart';
 /// * `angel_shelf.response` - The Angel [ResponseContext].
 AngelConfigurer supportShelf() {
   return (Angel app) async {
-    app.before.add((RequestContext req, ResponseContext res) async {
+    app.use((RequestContext req, ResponseContext res) async {
       // Inject shelf.Request ;)
       req.inject(
           shelf.Request,

test/embed_shelf_test.dart

@@ -38,7 +38,7 @@ main() {
 
     var app = new Angel()..lazyParseBodies = true;
     app.get('/angel', 'Angel');
-    app.after.add(embedShelf(handler, throwOnNullResponse: true));
+    app.use(embedShelf(handler, throwOnNullResponse: true));
     await app.configure(logRequests());
 
     server = await app.startServer(InternetAddress.LOOPBACK_IP_V4, 0);