Feature Request: Allow NTLM proxy negotiation config in Settings

[Barryrowe]

It's great that the npmo server can make use of a proxy, but many corporate environments have NTLM authenticated proxies which requires more than just the proxy URL. Allowing an admin to setup the UN/PW credentials for an account to negotiate with the proxy would be a nice flexible addition to the server.

It's possible to work around this with a third party product like CNTLM, but would be much nicer to have the negotiation handled within npmo.

[nexdrew]

@Barryrowe Thanks for creating this!