Ruby 1.9 and 2: LoadError: cannot load such file -- YAML

[mrGrazy]

It needs to be

require 'yaml' 

for newer rubies. This doesn't fail if you happen to use currencies with another library that requires yaml correctly.

[msaspence]

On osx this causes the same file to be loaded twice and a couple of warnings to be posted

For reference @mrGrazy's change is at lib/iso3217.rb:3