Enable manual uploads

```
Pretty much each time I run a benchmark, some results "fail to upload". Roughly
10% seem to be missing, making the whole web UI largely useless, in particular
since I can't find how to "manually upload" results.

I know where the .json files are, and so far I've been analyzing them manually
instead.

Here's an example where two runs failed to upload:

https://microbenchmarks.appspot.com/runs/6495c5ef-e7be-462c-86dd-c5573c219a67

Also, how can I remove broken/outdated/incomplete runs from the web UI? It
seems as if only some where associated with my account, and even for those
there is no delete option.
```

Original issue reported on code.google.com by `erich.sc...@gmail.com` on 15 Jun 2013 at 5:37