Switch pkg packages, pub, and dartdoc to use package: imports.

pkg/http/test/response_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.
 
 library response_test;
 
 import 'dart:async';
 import 'dart:io';
 
+import 'package:http/http.dart' as http;
 import 'package:unittest/unittest.dart';
-import '../lib/http.dart' as http;
 
 void main() {
   group('()', () {
     test('sets body', () {
       var response = new http.Response("Hello, world!", 200);
       expect(response.body, equals("Hello, world!"));
     });
 
     test('sets bodyBytes', () {
       var response = new http.Response("Hello, world!", 200);
@@ skipping 39 matching lines @@
       var streamResponse = new http.StreamedResponse(controller.stream, 200, 5);
       var future = http.Response.fromStream(streamResponse)
         .then((response) => response.bodyBytes);
       expect(future, completion(equals([104, 101, 108, 108, 111])));
 
       controller.add([104, 101, 108, 108, 111]);
       controller.close();
     });
   });
 }