RFC-7239 compliant reverse-proxy middleware for OWIN

To use the middleware in a OWIN startup:

    public void Configuration(IAppBuilder app)
    {
        app.UseForwardHeaders(options: default(ForwardedHeadersOptions));
    }

You can opt for a X-Forwarded-* standard of proxy headers or you can opt for the new RFC-7234 compliant forwarded headers. Using ForwardedHeadersOptions you can define your desired standard.