Looks like there is an error in RequestAuthenticator -> GetAuthenticationToken parameter order

[phclem]

    public AuthenticationToken GetAuthenticationToken(ApiRequest request)
    {
        var timestamp = (request.Timestamp).ToString(System.Globalization.CultureInfo.InvariantCulture);
        var signature = ComputeSignature(request);
        // the following construction has the parameters specified in an incorrect order
        // return new AuthenticationToken(_apiKey, signature, timestamp, _passphrase);
        // should be
        return new AuthenticationToken(_apiKey, _passphrase, signature, timestamp);
    }

[markwkjr]

@phclem I fixed this commit 284bba8c6f4efb2a3576659a346d52efbbe1cc0b. It has a bunch of other changes that I'm not sure are ready for a PR yet though :-/
It adds support for the PostOnly option in ordering, which I have tested and works. And then it has some unfinished code I was working on to support the Candles Endpoint