Convert pkg/http to use "package:" imports.

pkg/http/test/request_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 request_test;
 
 import 'dart:io';
 
-import '../../unittest/lib/unittest.dart';
-import '../lib/http.dart' as http;
-import '../lib/src/utils.dart';
+import 'package:unittest/unittest.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/src/utils.dart';
 import 'utils.dart';
 
 void main() {
   test('.send', () {
     startServer();
 
     var request = new http.Request('POST', serverUrl);
     request.body = "hello";
     var future = request.send().chain((response) {
       expect(response.statusCode, equals(200));
@@ skipping 367 matching lines @@
   });
 
   group('#toString()', () {
     test('includes the method and URL', () {
       var request = new http.Request('POST', dummyUrl);
       expect(request.toString(), 'POST $dummyUrl');
     });
   });
 }