Support providing localized string for country and currency code

[abuobaida]

[nekrich]

@abuobaida I think those funcs should be in Localize class, not String.

extension Localize {
	
	/// Returns current locale.
	///
	/// - Returns: current locale.
	final class func currentLocale() -> Locale {
		return Locale(identifier: Localize.currentLanguage())
	}
	
	/// Returns a localized string for a specified ISO 4217 currency code.
	///
	/// - Parameter currencyCode: ISO 4217 currency code the currency whose name you want.
	/// - Returns: Localized string for a specified ISO 4217 currency code.
	final class func localizedCurrency(_ currencyCode: String) -> String {
		return currentLocale()
			.localizedString(forCurrencyCode: currencyCode) ?? currencyCode
	}
	
	/// Returns the localized string for the specified country code.
	///
	/// - Parameter countryCode: The country code indicating the country whose name you want.
	/// - Returns: Localized string for the specified country code.
	final class func localizedCountry(_ countryCode: String) -> String {
		return (currentLocale() as NSLocale)
			.localizedString(forCountryCode: countryCode) ?? countryCode
	}
	
}

[abuobaida]

Thanks @nekrich, branch updated.