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

pkg/intl/test/number_format_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 number_format_test;
 
-import '../../../pkg/unittest/unittest.dart';
+import '../../../pkg/unittest/lib/unittest.dart';
 import '../lib/number_format.dart';
 import '../lib/intl.dart';
 
 /**
  * Tests the Numeric formatting library in dart.
  */
 var testNumbers = const {
   "0.001":  0.001,
   "0.01": 0.01,
   "0.1": 0.1,
@@ skipping 19 matching lines @@
     expect(number.format(3.14),"3.14");
   });
 
   test('Simple set of numbers', () {
     var number = new NumberFormat();
     for (var x in testNumbers.keys) {
       var formatted = number.format(testNumbers[x]);
       expect(formatted, x);
     }
   });
-}
+}