Many changes

Firstly, the loadSettings function tried to create the settings file if
it  does not exist.
Next, there is a new function: getStartingAmount, which gets the
starting amount of money.
Also getPlayerEconomy now works and addPlayerEconomy now checks for null
arguments
Now SMP main loads the settings
onPlayerJoined now loads / creates a new PlayerEconomy for the player

Also changed event priority to "HIGH"