Remove Windows Phone #if option (for now)
[XamFormsImageResize] Added Windows Phone

Also upgraded to Xamarin.Forms 1.2.3.
[XamFormsImageResize] Added Xamarin.Forms tag to metadata
[XamFormsImageResize] Added WinPhone screenshots.
[working-with] fonts, add Span C# example
[working-with] fonts FormattedString update