Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/wp-mail-smtp/src/Providers/AuthInterface.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace WPMailSMTP\Providers;
+
+/**
+ * Interface AuthInterface.
+ *
+ * @since 1.0.0
+ */
+interface AuthInterface {
+
+	/**
+	 * Whether user saved Client ID/App ID and Client Secret/App Password or not.
+	 * Both options are required.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return bool
+	 */
+	public function is_clients_saved();
+
+	/**
+	 * Whether we have an access and refresh tokens or not.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return bool
+	 */
+	public function is_auth_required();
+}