Island IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "IS",
    ...>    check_digits: "14",
    ...>    bank_code: "0159",
    ...>    branch_code: "26",
    ...>    national_check: nil,
    ...>    account_number: "0076545510730339"
    ...>  }
    ...>  |> IbanEx.Country.IS.to_string()
    "IS 14 0159 26 0076545510730339"