Updating openexchangerates.org support list

- taken from http://openexchangerates.org/api/currencies.json
- means the addition of [:btc, :eek, :ern, :ggp, :imp, :jep, :kyd,
:mtl, :xag, :xau, :zmw]
- now alphabetical
- whitespace
Adding additional currencies
- missing defunct currencies that are still be useful for historical purposes: Estonian Kroon (EEK) and Maltese Lira (MTL)
- adding gold and silver conversions as currencies XAU and XAG
- adding 3 different versions of GBP, which may be relevant - IMP, JEP and GGP