Provide some information on why upload fails

```
What steps will reproduce the problem?
1. Run tests (caliper 1.0-beta-1)
2. ...
3. Get "Some trials failed to upload. Consider uploading them manually." error

Not sure why, but uploads started failing. Could be an intermittent
connectivity problem.
The issue I have is two-fold:

(a) Error message does not indicated what is the root problem (I see that
Exception is passed to logger -- why it swallows it I don't know). It should,
to give an idea of what exactly happened
(b) Results should be stored locally; and path should be printed to let user
find them (perhaps these are already saved?)

```

Original issue reported on code.google.com by `tsaloranta@gmail.com` on 19 May 2013 at 4:38