test_s3:test_bucket_list_return_data_versioning bug

@zhangsw for this test case : s3tests.functional.test_s3:test_bucket_list_return_data_versioning
need to changes in **boto/s3/key.py endElement function** as well, otherwise test case always failed , could u help to check? Thanks
`def endElement(self, name, value, connection):
if name == 'Key':
self.name = value
elif name == 'ETag':
self.etag = value
elif name == 'IsLatest':
if value == 'true':
self.is_latest = True
else:
self.is_latest = False
elif name == 'LastModified':
self.last_modified = value
elif name == 'Size':
self.size = int(value)
elif name == 'StorageClass':
self.storage_class = value
elif name == 'Owner':
pass
elif name == 'VersionId':
self.version_id = value
else:
setattr(self, name, value)`

need to set key's 'Content-Encoding'