Added README, a bin/serve example server which can be used locally.

bin/serve.dart

Index: bin/serve.dart
diff --git a/bin/serve.dart b/bin/serve.dart
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+// Copyright (c) 2014, 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 'dart:io';
+
+import 'package:args/args.dart';
+import 'package:logging/logging.dart';
+import 'package:shelf/shelf_io.dart' as shelf_io;
+import 'package:http/http.dart' as http;
+import 'package:pub_server/shelf_pubserver.dart';
+
+import 'src/examples/file_repository.dart';
+import 'src/examples/http_proxy_repository.dart';
+import 'src/examples/cow_repository.dart';
+
+final Uri PubDartLangOrg = Uri.parse('https://pub.dartlang.org');
+
+
+main(List<String> args) {
+  var parser = argsParser();
+  var results = parser.parse(args);
+
+  var directory = results['directory'];
+  var host = results['host'];
+  var port = int.parse(results['port']);
+
+  if (results.rest.length > 0) {
+    print('Got unexpected arguments: "${results.rest.join(' ')}".\n\nUsage:\n');
+    print(parser.usage);
+    exit(1);
+  }
+
+  setupLogger();
+  runPubServer(directory, host, port);
+}
+
+runPubServer(String baseDir, String host, int port) {
+  var client = new http.Client();
+
+  var local = new FileRepository(baseDir);
+  var remote = new HttpProxyRepository(client, PubDartLangOrg);
+  var cow = new CopyAndWriteRepository(local, remote);
+
+  var server = new ShelfPubServer(cow);
+  print('Listening on http://$host:$port\n'
+        '\n'
+        'To make the pub client use this repository configure your shell via:\n'
+        '\n'
+        '    \$ export PUB_HOSTED_URL=http://$host:$port\n'
+        '\n');
+  return shelf_io.serve(server.requestHandler, host, port);
+}
+
+ArgParser argsParser() {
+  var parser = new ArgParser();
+
+  parser.addOption('directory',
+                   abbr: 'd',
+                   defaultsTo: 'pub_server-repository-data');
+
+  parser.addOption('host',
+                   abbr: 'h',
+                   defaultsTo: 'localhost');
+
+  parser.addOption('port',
+                   abbr: 'p',
+                   defaultsTo: '8080');
+  return parser;
+}
+
+void setupLogger() {
+  Logger.root.onRecord.listen((LogRecord record) {
+    var head = '${record.time} ${record.level} ${record.loggerName}';
+    var tail = record.stackTrace != null ? '\n${record.stackTrace}' : '';
+    print('$head ${record.message} $tail');
+  });
+}