Added Borgun provider to the currency endpoint

[jonoskar]

A different data scheme than Arion, M5 and Landsbankinn. However, Borgun API has far more currencies to offer so it's definitely a valuable provider.

Sample response:

results: [
    {
        currencyCode: "ALL",
        currencyDescription: "lek",
        currencyRate: 1.08005,
        country: "Albanía",
        countryEnglish: "Albania",
        countryCode: "ALB",
        rateDate: "10.2.2016"
    },
    {
        currencyCode: "DZD",
        currencyDescription: "denari, alsírskur",
        currencyRate: 1.25288,
        country: "Alsír",
        countryEnglish: "Algeria",
        countryCode: "DZA",
        rateDate: "10.2.2016"
    }
]

[jonoskar]

Yeah... I have nothing to do with those failing tests 😁

[koddsson]

LGTM

[kristjanmik]

Great job @jonoskar! Thanks for contributing 👍
The endpoint will not be deployed unless we fix the tests. I will take a look over the weekend.

[kristjanmik]

Me and @koddsson did some shovelling and your code is now in production at https://apis.is/currency/borgun 🎉