Call analytics.track on receipt page

ECOM-4101

lms/static/js/commerce/views/receipt_view.js

@@ -47,6 +47,8 @@ var edx = edx || {};
 
             this.trackLinks();
 
+            this.trackPurchase(data);
+
             this.renderCourseNamePlaceholder(this.courseKey);
 
             providerId = this.getCreditProviderId(data);
@@ -77,6 +79,14 @@ var edx = edx || {};
             $('#error-container').removeClass('hidden');
         },
 
+        trackPurchase: function (order) {
+            window.analytics.track("Completed Order", {
+                orderId: order.number,
+                total: order.total_excl_tax,
+                currency: order.currency
+            });
+        },
+
         render: function () {
             var self = this,
                 orderId = this.ecommerceOrderNumber || this.ecommerceBasketId || $.url('?payment-order-num');