Merge pull request #22 from samunohito/feature/#3_add_device_horizontal

ビューの向きに不備があったので修正

Author: samunohito

SimpleVolumeMixer/UI/Views/Controls/AudioDevicesSubHorizontalPage.xaml

@@ -18,7 +18,7 @@
             <Border
                 Padding="8"
                 BorderThickness="0"
-                Height="{Binding ViewportHeight, RelativeSource={RelativeSource FindAncestor, AncestorType=ScrollViewer}}">
+                Width="{Binding ViewportWidth, RelativeSource={RelativeSource FindAncestor, AncestorType=ScrollViewer}}">
                 <ItemsControl
                     ItemsSource="{Binding Devices}"
                     ItemsPanel="{StaticResource HorizontalAudioDevicesPanelTemplate}"