Rename view-configuration to view_configuration to make analyzer happy.

Analyzer was complaining about '-' not being an allowed character
in dart file names.

R=jamesr@chromium.org

examples/stocks/lib/stock_menu.dart

@@ -4,7 +4,7 @@
 
 import 'package:sky/framework/components/popup_menu.dart';
 import 'package:sky/framework/fn.dart';
-import 'package:sky/framework/theme/view-configuration.dart';
+import 'package:sky/framework/theme/view_configuration.dart';
 
 class StockMenu extends Component {
   static final Style _style = new Style('''