Add a pub command for managing uploaders for packages.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index 835a09d5f0e8cfa0f84658caf682027d6b13f81b..0fefb2280099da12b1adbab7561ed8ae4bf86121 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -15,6 +15,7 @@ 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 'entrypoint.dart';
 import 'exit_codes.dart' as exit_codes;
@@ -39,6 +40,7 @@ Map<String, PubCommand> get pubCommands {
     'install': new InstallCommand(),
     'publish': new LishCommand(),
     'update': new UpdateCommand(),
+    'uploader': new UploaderCommand(),
     'version': new VersionCommand()
   };
   for (var command in commands.values) {