Better error message instead of "paracurl.Exception: (-5, 'PC_ERR_HTTP : bad HTTP status code')"

[tobltobs]

If someone messes up the configuration by including folders, misspelling, forgetting to upload the blend files archive or similar mistakes he will get a cryptic paracurl.Exception: (-5, 'PC_ERR_HTTP : bad HTTP status code') error.
Maybe it would help if there would be a more specific error message like "Could not find blend file ...".
The origin of the error is at:
File "/usr/local/lib/python2.7/dist-packages/brenda/node.py", line 382, in get_s3_project file_len, etag = aws.s3_get(conf, s3url, fn, etag=etag)

And thank you for this great tool.