Allow the bank to function as a coder.

[ioquatix]

Allows a bank instance to function as a coder, which accepts more reasonable "human" formatted amounts:

#12

require 'latinum/currencies/global'

class T < ApplicationRecord
  BANK = Latinum::Bank.new.tap do |bank|
    bank.import(Latinum::Currencies::Global)
  end
  
  serialize :amount, coder: BANK
end