Is the URL approach supported for all file systems? #271

I attempted this command:

opener.opendir('s3://KEYPART:SECRETPART@BUCKET/path-within-bucket')

Results in the error "BotoClientError: Bucket names cannot contain upper-case characters when using either the sub-domain or virtual hosting calling format."

An analogous command using ftp://, sftp:// or osfs:// works fine.

Is the URL approach to specifying a connection not implemented for all file systems?