NAT: REQUEST DOCUMENT and NTLM Authentication

Request Document should support NTLM Authentication.

Reason:
NTLM is a more secure logon process because it uses an encrypted challenge/response protocol to authenticate a user without sending the user's password over the wire.
For the authentication dialog several negotiation steps between client and server are necessary. This requires a persistent socket connection over a series of HTTP requests.

Problem:
Natural does not support a persistent socket connection over several requests.