Feature Request: NTLM Authentication

[mubix]

It would be really awesome if this project supported NTLM authentication. I've been trying to get it to work by adding the required pieces to lib/webdav.go, but I think more base changes are needed. I can get the Type 1 message incoming, parse it and send the Type 2 message back, but unfortunately it doesn't get the Type 3 message back. Still investigating why that might be. I'm relatively new to Golang so this might be outside of my abilities.