PSR-4 compliance & autoloader

Lib/Exception/BookNotFoundException.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace BSR\Lib\Exception;
+
+class BookNotFoundException extends WebException {
+    public function __construct($code) {
+        parent::__construct('BookNotFound', "The book with code $code was not found", -404);
+    }
+}