Added all SEPA countries (IBANs from European Union countries) and minimal test coverage for countries

lib/iban_ex/country/sk.ex

@@ -0,0 +1,17 @@
+defmodule IbanEx.Country.SK do
+  @moduledoc """
+  Slovakia IBAN parsing rules
+
+  ## Examples
+
+    iex> %IbanEx.Iban{country_code: "SK", check_digits: "31", bank_code: "1200", branch_code: nil, national_check: nil, account_number: "0000198742637541"}
+    iex> |> IbanEx.Country.SK.to_string()
+    "SK 31 1200 0000198742637541"
+
+  """
+
+  @size 24
+  @rule ~r/^(?<bank_code>[0-9]{4})(?<account_number>[0-9]{16})$/i
+
+  use IbanEx.Country.Template
+end