Add external links for tasks with plugin api

app/ExternalLink/AttachmentLink.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Kanboard\ExternalLink;
+
+use Kanboard\Core\ExternalLink\ExternalLinkInterface;
+
+/**
+ * Attachment Link
+ *
+ * @package  externalLink
+ * @author   Frederic Guillot
+ */
+class AttachmentLink extends BaseLink implements ExternalLinkInterface
+{
+    /**
+     * Get link title
+     *
+     * @access public
+     * @return string
+     */
+    public function getTitle()
+    {
+        $path = parse_url($this->url, PHP_URL_PATH);
+        return basename($path);
+    }
+}