Restructure pkg/unittest and pkg/webdriver to follow the pub conventions.

pkg/webdriver/lib/src/base64decoder.dart

Index: pkg/webdriver/lib/src/base64decoder.dart
===================================================================
--- pkg/webdriver/lib/src/base64decoder.dart	(revision 0)
+++ pkg/webdriver/lib/src/base64decoder.dart	(working copy)
@@ -1,3 +1,9 @@
+// Copyright (c) 2011, 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.
+
+part of webdriver;
+
 /**
  * A simple base64 decoder class, used to decode web browser screenshots
  * returned by WebDriver.