Composer: Add vendor directry

- Add gitignore to avoid committing libraries' .git folder

vendor/composer/autoload_classmap.php

@@ -0,0 +1,12 @@
+<?php
+
+// autoload_classmap.php @generated by Composer
+
+$vendorDir = dirname(dirname(__FILE__));
+$baseDir = dirname($vendorDir);
+
+return array(
+    'Friendica\\Core\\Config' => $baseDir . '/include/Core/Config.php',
+    'Friendica\\Core\\PConfig' => $baseDir . '/include/Core/PConfig.php',
+    'Friendica\\ParseUrl' => $baseDir . '/include/ParseUrl.php',
+);