gcloud.storage.bucket.Bucket.upload_file defaults 'key' to None

[tseaver]

The API cannot do anything useful with the default: either it should be a required argument, or else the method should do something sensible if it is not passed. E.g., one might crack the last element of the filename off and use that as a default key.

[tseaver]

The docstring actually requires the latter choice:

https://github.com/GoogleCloudPlatform/gcloud-python/blob/1f2aaf3606802f4f02eeb30e22e1082ef7f4594e/gcloud/storage/bucket.py#L234