Add library names to many sky libraries

- Analyzer complains about libraries not having names. This adds names to many libraries.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1150433002

examples/stocks/lib/stock_arrow.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+library stock_arrow;
+
 import 'dart:math';
 import 'package:sky/framework/fn.dart';
 import 'package:sky/framework/layout.dart';

examples/stocks/lib/stock_data.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+library stock_data;
+
 import 'dart:convert';
 import 'dart:math';
 import 'package:sky/framework/net/fetch.dart';

examples/stocks/lib/stock_list.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+library stock_list;
+
 import 'package:sky/framework/components/fixed_height_scrollable.dart';
 import 'package:sky/framework/fn.dart';
 import 'stock_data.dart';