message: Add horizontal scrollbar support (win)
diff: </ControlTemplate.Triggers>
  </ControlTemplate>
  + <ControlTemplate x:Key="Toggl.HorizontalScrollBar" TargetType="{x:Type ScrollBar}">
  + <Grid Background="Transparent">
  + <Track
  + Name="PART_Track"
  + IsDirectionReversed="true"
  + VerticalAlignment="Bottom"
  + Height="{TemplateBinding Height}">
  + <Track.DecreaseRepeatButton>
  + <RepeatButton
  + Style="{StaticResource Toggl.ScrollBarPageButton}"
  + Command="ScrollBar.PageUpCommand"
  + />
  + </Track.DecreaseRepeatButton>
  + <Track.Thumb>
  + <Thumb Style="{StaticResource Toggl.ScrollBarThumb}" />
  + </Track.Thumb>
  + <Track.IncreaseRepeatButton>
  + <RepeatButton
  + Style="{StaticResource Toggl.ScrollBarPageButton}"
  + Command="ScrollBar.PageDownCommand"
  + />
  + </Track.IncreaseRepeatButton>
  + </Track>
  + </Grid>
  + <ControlTemplate.Triggers>
  + <Trigger Property="IsMouseOver" Value="False">
  + <Setter TargetName="PART_Track" Property="Height" Value="2" />
  + </Trigger>
  + </ControlTemplate.Triggers>
  + </ControlTemplate>
  +
  <Style x:Key="Toggl.CustomScrollBar" TargetType="{x:Type ScrollBar}">
  <Setter Property="SnapsToDevicePixels" Value="True"/>
  <Setter Property="OverridesDefaultStyle" Value="true"/>
  <Setter Property="Height" Value="Auto" />
  <Setter Property="Margin" Value="0 0 2 0" />
  <Setter Property="Template" Value="{StaticResource Toggl.VerticalScrollBar}" />
  + <Style.Triggers>
  + <Trigger Property="Orientation" Value="Horizontal">
  + <Setter Property="Height" Value="4" />
  + <Setter Property="Width" Value="Auto" />
  + <Setter Property="Template" Value="{StaticResource Toggl.HorizontalScrollBar}" />
  + </Trigger>
  + </Style.Triggers>
  </Style>
  <Style TargetType="ScrollViewer" x:Key="Toggl.CustomScrollViewer">
  <ControlTemplate TargetType="ScrollViewer">
  <Border BorderThickness="0">
  <Grid Background="{TemplateBinding Background}">
  + <Grid.RowDefinitions>
  + <RowDefinition Height="*" />
  + <RowDefinition Height="Auto" />
  + </Grid.RowDefinitions>
  <Grid.ColumnDefinitions>
  <ColumnDefinition Width="*"/>
  <ColumnDefinition Width="Auto"/>
  ContentTemplate="{TemplateBinding ContentTemplate}"/>
  <ScrollBar x:Name="PART_VerticalScrollBar"
  + Grid.Row="0"
  + Grid.Column="1"
  + Orientation="Vertical"
  IsTabStop="False"
  - Grid.Column="1" Orientation="Vertical"
  Cursor="Arrow"
  Maximum="{TemplateBinding ScrollableHeight}"
  Minimum="0"
  Value="{Binding VerticalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}"
  Style="{StaticResource Toggl.CustomScrollBar}"/>
  + <ScrollBar x:Name="PART_HorizontalScrollBar"
  + Grid.Row="1"
  + Grid.Column="0"
  + Orientation="Horizontal"
  + IsTabStop="False"
  + Cursor="Arrow"
  + Maximum="{TemplateBinding ScrollableHeight}"
  + Minimum="0"
  + ViewportSize="{TemplateBinding ViewportHeight}"
  + Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
  + Value="{Binding HorizontalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}"
  + Style="{StaticResource Toggl.CustomScrollBar}"/>
  </Grid>
  </Border>
  </ControlTemplate>
  