Relaxed mode

[essen]

Since we don't always talk to HTTP-compliant services (such as the barely used S3) we need a way to work when harmless faults are encountered. A relaxed mode would do that. We could remain strict by default and have a general option to be relaxed only for the harmless faults.

For now the relaxed mode would only accept the following errors:

• 204 responses with a 0-length content-length header
• ...