[Fixes #90] Currency Resource added

Author: tareqtms

lib/Currency.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: Tareq
+ * Date: 6/10/2019
+ * Time: 11:22 PM
+ *
+ * @see https://help.shopify.com/en/api/reference/store-properties/currency Shopify API Reference for Currency
+ */
+
+namespace PHPShopify;
+
+
+class Currency extends ShopifyResource
+{
+    /**
+     * @inheritDoc
+     */
+    protected $resourceKey = 'currency';
+
+    /**
+     * @inheritDoc
+     */
+    public $readOnly = true;
+
+    /**
+     * @inheritDoc
+     */
+    public function pluralizeKey()
+    {
+        return 'currencies';
+    }
+}

tests/CurrencyTest.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: Tareq
+ * Date: 6/10/2019
+ * Time: 11:26 PM
+ */
+
+namespace PHPShopify;
+
+
+class CurrencyTest
+{
+
+}