Improve infinite redirection error message

Right now an infinite redirection produces a traceback ending with an error like:

```
twisted.web._newclient.ResponseFailed: [<twisted.python.failure.Failure twisted.web.error.InfiniteRedirection: 302 Infinite redirection detected to http://feedpress.me/jlongster>]
```

Add a special case for this one as it is a failure condition seen in the wild.