Estonian IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "EE",
    ...>    check_digits: "38",
    ...>    bank_code: "22",
    ...>    branch_code: "00",
    ...>    national_check: "5",
    ...>    account_number: "22102014568"
    ...>  }
    ...>  |> IbanEx.Country.EE.to_string()
    "EE 38 22 00 22102014568 5"