Replace multiplier with minimum stake

[kermankohli]

Remove the whole multiplier system and instead replace it with a minimum stake. The minimum stake starts off based on the highest total stake of an individual. It then decreases exponentially at a rate of 0.5. This is based close to most currencies which have a Gini co-efficient between 0.6 and 0.8. There is a bit of a difference in the proposed 0.5 however it's better to under-fit the data that over-fit it as it will lead to increased collisions (race conditions leading to wasted gas).