Fixes album export by reducing memory usage of the scripts.

Chunks the output buffer to 4kB chunks. This means the Download.php
script will no longer run out of memory when trying to stream a
tar file the output buffer.

app.php

@@ -27,6 +27,6 @@ set_error_handler('ErrorHandler::handleError');
 ini_set("display_errors", DEBUG ? "On" : "Off");
 
 // The real magic starts here!
-ob_start();
+ob_start(null, 32768);
 Dispatcher::dispatch();
 ob_end_flush();