Move Introduction to new depository paradigm

src/Contact/Introduction/Exception/IntroductionPersistenceException.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Friendica\Contact\Introduction\Exception;
+
+class IntroductionPersistenceException extends \RuntimeException
+{
+	public function __construct($message = "", \Throwable $previous = null)
+	{
+		parent::__construct($message, 500, $previous);
+	}
+}