Composer fixes (#157)

* Composer fix

Author: Ynhockey

GigyaAction.php

@@ -123,7 +123,9 @@ public function __construct() {
 	public function init()
 	{
 		/* Require SDK libraries */
-		require_once GIGYA__PLUGIN_DIR . 'vendor/autoload.php'; /* If the plugin is installed by Composer as a `wordpress-plugin`, this becomes unnecessary, but require_once makes sure it's not included again */
+		if ( file_exists( GIGYA__PLUGIN_DIR . 'vendor/autoload.php' ) ) { /* If the plugin is installed by Composer as a `wordpress-plugin`, this becomes unnecessary, but require_once makes sure it's not included again */
+			require_once GIGYA__PLUGIN_DIR . 'vendor/autoload.php';
+		}
 		require_once GIGYA__PLUGIN_DIR . 'cms_kit/GigyaJsonObject.php';
 		require_once GIGYA__PLUGIN_DIR . 'cms_kit/GigyaUserFactory.php';
 		require_once GIGYA__PLUGIN_DIR . 'cms_kit/GigyaProfile.php';