Modify exp formula to make leveling up attainable.

[dmccoystephenson]

After awhile it becomes nearly impossible to level up. We should modify the formula.

[dmccoystephenson]

Switching the experienceIncreaseFactor and currentLevel variables should do the trick.

Old formula (red): baseExperienceRequirement*experienceIncreaseFactor^currentLevel

Proposed formula (blue): baseExperienceRequirement*currentLevel^experienceIncreaseFactor