Retrieves a bucket if it exists, otherwise creates it.

def _get_or_create_bucket(self, name):
        """Retrieves a bucket if it exists, otherwise creates it."""
        try:
            return self.connection.get_bucket(name)
        except S3ResponseError, e:
            if AUTO_CREATE_BUCKET:
                return self.connection.create_bucket(name)
            raise ImproperlyConfigured, ("Bucket specified by "
            "AWS_STORAGE_BUCKET_NAME does not exist. Buckets can be "
            "automatically created by setting AWS_AUTO_CREATE_BUCKET=True")