Port the old system to a more advanced setup.

.php_cs

@@ -0,0 +1,12 @@
+<?php
+
+$finder = PhpCsFixer\Finder::create()
+    ->exclude('vendor')
+    ->in(__DIR__);
+
+return PhpCsFixer\Config::create()
+    ->setUsingCache(true)
+    ->setRules([
+        '@PSR2'              => true,
+        'single_quote'       => true,
+    ])->setFinder($finder);