Add data_type to Fact
Add ISO 4217 currency codes
Work in progress Fact#formatted_value
Add numeric format implementation for percentage
Add data type selections to admin fact form
Make default currency GBP
Add optgroup helper for currency codes
Add explanatory label for Chinese Yen
Refactor formatting methods into a module
Add facts helper specs
Expose formatted_value via the API
Make subclasses for data types
Move formatting into presenter
Remove unused lib
Add fact type handling to controller
Refactor admin facts form
Test various formatting options in API response
Add formatted value to admin index
Remove unused fields
Move currency symbols into yaml