Icons to differentiate Issues with Pull Requests

[rprouse]

Add to the issue list. Add icon or info to the issue viewer too.

[rprouse]

<DataGridTemplateColumn Width="20" CanUserResize="False">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Image Name="IssueImage" Source="/UserCenterExtension;component/Images/Bug.png" Stretch="None" />
            <DataTemplate.Triggers>
                <DataTrigger Binding="{Binding Path=Enhancement}" Value="True">
                    <Setter TargetName="IssueImage" Property="Source" Value="/UserCenterExtension;component/Images/Enhancement.png" />
                </DataTrigger>
            </DataTemplate.Triggers>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>