Work around for servers that send unquoted algorithm information

[akurz]

Please consider to merge this pull request as a workaround for misbehaving(?) servers that don't quote the algorithm header information.

thx & cheers,
Andreas

[peter-mogensen]

I honestly don't think the servers are misbehaving.
According to RFC7235 Appendix C auth-param values only need to be quoted if they cannot be represented as a RFC7230 token.

So ... yeah... that's a bug. But it's a bug caused by the rather simple parsing of the WWW-Authenticate header, using strings.Split() and strings.Contains() on '"', which you patch then build upon also doing it for '=' ...
I don't think your patch introduces more cases where it'll fail for valid input (apart from also capturing any BWS between = and token), but I think this in general needs an overhaul to be an actual RFC7616 implementation.