lib: Add HttpException as base class for HTTP exceptions

refs #6281

library/Icinga/Exception/Http/HttpException.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Icinga\Exception\Http;
+
+use Icinga\Exception\IcingaException;
+
+/**
+ * Base class for HTTP exceptions
+ */
+abstract class HttpException extends IcingaException
+{
+
+}