Support format currency

Support format currency, extending `formatNumber` to able to format currency. Currencies are also numbers, they're a part of Number module.

#### TODO
- [ ] Implementation
- [ ] Unit and Functional tests
- [ ] Docs;

#### API Examples

```javascript
Globalize.formatNumber( 1337, { currency: "EUR" } );   
// 1337,00 €
Globalize.formatNumber( 53.07, { currency: "USD" } );  
// $ 53.07
```

Adds currency as option

#### CLDR
- [Number Patterns](http://cldr.unicode.org/translation/number-patterns) 
- [Currency Symbols & Names](http://cldr.unicode.org/translation/currency-names)
- [Currency Formats](http://www.unicode.org/reports/tr35/tr35-numbers.html#Currency_Formats)
- [Currencies](http://www.unicode.org/reports/tr35/tr35-numbers.html#Currencies)


Reference: https://github.com/jquery/globalize/issues/238