Update 404 response (#163)

Updating for new SPL standard.

index.php

@@ -48,7 +48,7 @@
 }
 
 if(preg_match("/^(.*)\.(gif|jpg|png|jpeg|tiff|bmp|css|js|less|map|html|php|zip|rar|gz|ttf|woff|ico)$/i", $_SERVER['REQUEST_URI'])) {
-	header('HTTP/1.0 404 Not Found');
+	http_response_code(404);
 	exit;
 }