Remove BG graphics

[adamhope]

Once we had real data it became obvious the D3 graphs could stand on their own. We only put them in because the smaller network graphs we tested with looked terrible.

I think we should have completely separate screens for the leaderboard, instructions and network graph. We could then either rotate them around on a single screen or display each one on a separate screen. As far as I'm aware the fixed size graphics are also the only thing at the moment stopping this from working on tablets and mobiles etc. It would be nice if participants could load up the network graph on their phone and display it or keep the leader board in their pocket for easy reference.