Roll Observatory packages and add a roll script

packages/quiver/test/time/all_tests.dart

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-library quiver.time;
+library quiver.time.all_tests;
 
-part 'src/time/clock.dart';
-part 'src/time/duration_unit_constants.dart';
+import 'clock_test.dart' as clock;
+
+main() {
+  clock.main();
+}