Update color and fill for QR code

[cnorm35]

Not something we have to deal with now but we'll need to update the QR code generation code to allow the option for printing in the future. Maybe this is something we can update to generate a SVG on the fly and render in a view instead of creating the PNG and attaching.

https://github.com/whomwah/rqrcode#as_svg