Add option to enable % instead of rank / level

[petrvecera]

Because each leaderboard has a different amount of players it should be possible to enable % instead of level / rank. That way we can compare player skill across different leaderboards.

I find it extremely useful because leaderboard Rank and Level were never a reliable way to compare skill between different factions with substantially different playerbase sizes. However, I also just realised you guys have a replacement for MakoCelo that's very clean and easy to use, so I wouldn't mind making a feature request of adding the percentage ranks to the table, if possible.