Features/http parameters

[mickael-finastream]

Permit to pass variables in url as AdditionalParameters.

var httpAdapterConnectionParameters = new HttpAdapterConnectionParameters{
Url = "https://www.google.com/search?q={{AdditionalParameters.query}}"
}

 contextStream
  .FromConnector("get from http", "MyHttpSourceForAdditionalParameters")
  .Select(
    "select",
    i =>
    {
      if (((HttpFileValueMetadata)i.Metadata).Parameters.AdditionalParameters == null)
      {
        ((HttpFileValueMetadata)i.Metadata).Parameters.AdditionalParameters = new Dictionary<string, string>();
      }
      (HttpFileValueMetadata)i.Metadata).Parameters.AdditionalParameters.Add("query", "Cat");
      return i;
    }
  )...

Also add a more permissive way to set DefaultHeaders in client by using : TryAddWithoutValidation