Expanding #246

[lokka30]

I realised I missed a few things in #247 to resolve #246.

• The reason we had getStartingBalance implemented inside Currency is because we want whoever is registering the Currency to provide the logic for giving the starting balance for a particular Account.

  • However, the change we made for making getStartingBalance accept an Account rather than a player UUID is still good.
  • So all we need to do is move the new getStartingBalance method back into Currency.

• And we forgot to do something: make the decimal character mapped to a Locale.