Kellner's own files go into package statistics

Serving an empty directory, kellner has this output:

```
This repository contains 3 packages with an accumulated size of 20 bytes.

Name    Last Modified   Size    Description
Packages    2015-12-16T17:53:13Z    0   
Packages.gz 2015-12-16T17:53:13Z    20  
Packages.stamps 2015-12-16T17:53:13Z    0   
```

I think these files should not go into the statistics.
