Move custom libs to the source tree

libs/SimpleValidator/Validators/NotEmpty.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace SimpleValidator\Validators;
+
+class NotEmpty extends Base
+{
+    public function execute(array $data)
+    {
+        if (array_key_exists($this->field, $data)) {
+            return $data[$this->field] !== null && $data[$this->field] !== '';
+        }
+
+        return true;
+    }
+}