Make Router::getModuleClass throw exceptions

- Add new MethodNotAllowedModule
- Add new Module->determineClass catch blocks
- Update Module and Router tests

src/Module/HTTPException/PageNotFound.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Friendica\Module\HTTPException;
+
+use Friendica\BaseModule;
+use Friendica\Core\L10n;
+use Friendica\Network\HTTPException;
+
+class PageNotFound extends BaseModule
+{
+	public static function content()
+	{
+		throw new HTTPException\NotFoundException(L10n::t('Page not found.'));
+	}
+}