Make "--no-packages-dir" the default.

test/get/hosted/get_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:pub/src/exit_codes.dart' as exit_codes;
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   integration('gets a package from a pub server', () {
     servePackages((builder) => builder.serve("foo", "1.2.3"));
 
     d.appDir({"foo": "1.2.3"}).create();
 
     pubGet();
 
     d.cacheDir({"foo": "1.2.3"}).validate();
-    d.packagesDir({"foo": "1.2.3"}).validate();
+    d.appPackagesFile({"foo": "1.2.3"}).validate();
   });
 
   integration('URL encodes the package name', () {
     serveNoPackages();
 
     d.appDir({"bad name!": "1.2.3"}).create();
 
     pubGet(
         error: new RegExp(
           r"Could not find package bad name! at http://localhost:\d+\."),
@@ skipping 15 matching lines @@
         "hosted": {
           "name": "foo",
           "url": server.port.then((port) => "http://localhost:$port")
         }
       }
     }).create();
 
     pubGet();
 
     d.cacheDir({"foo": "1.2.3"}, port: server.port).validate();
-    d.packagesDir({"foo": "1.2.3"}).validate();
+    d.appPackagesFile({"foo": "1.2.3"}).validate();
   });
 }