title: HttpRequest.Files is empty when posting file through HttpClient
body: <p>Server-side:</p>
  
  <pre><code>    public HttpResponseMessage Post([FromUri]string machineName)
      {
          HttpResponseMessage result = null;
          var httpRequest = HttpContext.Current.Request;
  
          if (httpRequest.Files.Count &gt; 0 &amp;&amp; !String.IsNullOrEmpty(machineName))
          ...
  </code></pre>
  
  <p>Client-side:</p>
  
  <pre><code>    public static void PostFile(string url, string filePath)
      {
          if (String.IsNullOrWhiteSpace(url) || String.IsNullOrWhiteSpace(filePath))
              throw new ArgumentNullException();
  
          if (!File.Exists(filePath))
              throw new FileNotFoundException();
  
          using (var handler = new HttpClientHandler { Credentials=  new NetworkCredential(AppData.UserName, AppData.Password, AppCore.Domain) })
          using (var client = new HttpClient(handler))
          using (var content = new MultipartFormDataContent())
          using (var ms = new MemoryStream(File.ReadAllBytes(filePath)))
          {
              var fileContent = new StreamContent(ms);
              fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
              {
                  FileName = Path.GetFileName(filePath)
              };
              content.Add(fileContent);
              content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
  
              var result = client.PostAsync(url, content).Result;
              result.EnsureSuccessStatusCode();
          }
      }   
  </code></pre>
  
  <p>At the server-side httpRequest.Files collection is always empty. But headers (content-length etc...) are right.</p>