Digest authentication on Linux/OSX may not work for HTTP transport

[mconnew]

This is due to an issue in HttpClientHandler in corefx. See dotnet/corefx#9672

[mconnew]

This is only an issue when communicating with a server which isn't using digest authentication against a domain. With a WCF service using the built-in digest authentication there should be no problem.

[mconnew]

The issue is that the username is sent as realm\username on some platforms, and as realm\username on others, even when the realm specified by the server matches. IIS is tolerant of this when using integrated authentication, but other platforms may not be.

[roncain]

I see the CoreFx issue https://github.com/dotnet/corefx/issues/9672 is slated for 1.2, so this will probably not be available in 1.1