Preemptive Kerberos auth for Windows

[laurivosandi]

On UNIX requests Kerberos module allows using force_preemptive=True, which tells the client to immideately send GSSAPI headers. On Windows this is not currently supported, perhaps this is possible from PowerShell?

https://github.com/laurivosandi/certidude/blob/master/certidude/cli.py#L439