Revert "Revert "Language names via intl library.""

This reverts commit 4f35efa0ba.

library/intl/src/Currency/CurrencyRepositoryInterface.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace CommerceGuys\Intl\Currency;
+
+/**
+ * Currency repository interface.
+ */
+interface CurrencyRepositoryInterface
+{
+    /**
+     * Returns a currency instance matching the provided currency code.
+     *
+     * @param string $currencyCode   The currency code.
+     * @param string $locale         The locale (i.e. fr-FR).
+     * @param string $fallbackLocale A fallback locale (i.e "en").
+     *
+     * @return CurrencyInterface
+     */
+    public function get($currencyCode, $locale = null, $fallbackLocale = null);
+
+    /**
+     * Returns all available currency instances.
+     *
+     * @param string $locale         The locale (i.e. fr-FR).
+     * @param string $fallbackLocale A fallback locale (i.e "en").
+     *
+     * @return array An array of currencies implementing the CurrencyInterface,
+     *               keyed by currency code.
+     */
+    public function getAll($locale = null, $fallbackLocale = null);
+}