When I run the tests, I get an s3 config error:
```
======================================================================
ERROR: Failure: NoSectionError (No section: 's3')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/ddaniels/code/ve_luigi/lib/python2.7/site-packages/nose/loader.py", line 413, in loadTestsFromName
    addr.filename, addr.module)
  File "/Users/ddaniels/code/ve_luigi/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "/Users/ddaniels/code/ve_luigi/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "/Users/ddaniels/code/luigi/test/s3_test.py", line 21, in <module>
    from luigi.s3 import S3Target, S3Client, client
  File "/Users/ddaniels/code/luigi/luigi/s3.py", line 190, in <module>
    client = S3Client()
  File "/Users/ddaniels/code/luigi/luigi/s3.py", line 48, in __init__
    aws_access_key_id = configuration.get_config().get('s3', 'aws_access_key_id')
  File "/Users/ddaniels/code/luigi/luigi/configuration.py", line 45, in get
    return self._get_with_default(ConfigParser.get, section, option, default)
  File "/Users/ddaniels/code/luigi/luigi/configuration.py", line 35, in _get_with_default
    return method(self, section, option)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ConfigParser.py", line 567, in get
    raise NoSectionError(section)
NoSectionError: No section: 's3'
```