Add 2019 uk party colours

[bobhaslett]

I’ve added the UK political colours that we used in the 2019 election. I have also used the correct party names ie 'Labour' with a cap L and Sinn Fin rather than sf. I’ve done this because it will mean that the chart doesn’t have to be edited as much at the point of production with regard to labelling lines etc. But this will mean that column headings in datasets will have to follow the same protocol. I suspect this will cause objections, so its more a conversation starter as to how we go about this for the production efficiency