add cache list command to pub

utils/pub/pub.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.
 
 /// The main entrypoint for the pub command line application.
 library pub;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
 import '../../pkg/args/lib/args.dart';
 import '../../pkg/pathos/lib/path.dart' as path;
 
 import 'command_help.dart';
 import 'command_install.dart';
 import 'command_lish.dart';
 import 'command_update.dart';
 import 'command_uploader.dart';
 import 'command_version.dart';
+import 'command_cache.dart';
 import 'entrypoint.dart';
 import 'exit_codes.dart' as exit_codes;
 import 'http.dart';
 import 'io.dart';
 import 'log.dart' as log;
 import 'package.dart';
 import 'pubspec.dart';
 import 'sdk.dart' as sdk;
 import 'source.dart';
 import 'source_registry.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 import 'version.dart';
 
 /// The commands that Pub understands.
 Map<String, PubCommand> get pubCommands {
   var commands = {
+    'cache': new CacheCommand(),
     'help': new HelpCommand(),
     'install': new InstallCommand(),
     'publish': new LishCommand(),
     'update': new UpdateCommand(),
     'uploader': new UploaderCommand(),
     'version': new VersionCommand()
-  };
+   };
   for (var command in commands.values.toList()) {
     for (var alias in command.aliases) {
       commands[alias] = command;
     }
   }
   return commands;
 }
 
 /// The parser for arguments that are global to Pub rather than specific to a
 /// single command.
@@ skipping 264 matching lines @@
     if (exception is HttpException || exception is HttpParserException ||
         exception is SocketIOException || exception is PubHttpException) {
       return exit_codes.UNAVAILABLE;
     } else if (exception is FormatException) {
       return exit_codes.DATA;
     } else {
       return 1;
     }
   }
 }