Server based accounts and settings. Added global leaderboard.
Bank class has been redone with hooks for 3rd party cogs.
The old ones have been removed, there was no way to keep backwards compatibility.
Since the bank.json format changed, once a user registers a bank account on a server if they're already present in the old format they'll keep their old balance.
Mod commands are now logged into data/mod/mod.log
Economy events are logged into data/economy/economy.log
Added !bank set to set credits (admin/owner)
Added !bank transfer to transfer credits between bank accounts
Modified !bank balance, it can now show the balance of other users too
