Multiplayer + Leaderboard: Multiple leaderboards

[shaunli8]

leaderboard class now has an argument key which determines what localStorage key the leaderboard is listening to.

• Changes to _sass/minima/platformer-styles.scss for height and scroll behavior
• "Old" leaderboard system moved into the new "Server Leaderboard" button
• Added local leaderboard button (This does not function currently)

Future changes (this does not indicate final product)

• Leaderboard button will change from local or server leaderboard depending on Multiplayer true/false state

Pull Request
Small Pull Request to set game back to true multiplayer