Update charted to 0.4.8 and roll

packages/usage/test/uuid_test.dart

 // 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.
 
 library usage.uuid_test;
 
 import 'package:test/test.dart';
-import 'package:usage/src/uuid.dart';
+import 'package:usage/uuid/uuid.dart';
 
 main() => defineTests();
 
 void defineTests() {
   group('uuid', () {
     // xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
     test('simple', () {
       Uuid uuid = new Uuid();
       String result = uuid.generateV4();
       expect(result.length, 36);
@@ skipping 45 matching lines @@
 
       uuid = new Uuid();
       for (int i = 0; i < 64; i++) {
         String val = uuid.generateV4();
         expect(set, isNot(contains(val)));
         set.add(val);
       }
     });
   });
 }