Setup.py properly declares dependencies

Fixes #15
Other setup.py improvements

* ISC license
* Add classifiers
Merge pull request #17 from davidfischer/setup-deps

Setup.py properly declares dependencies
Merge branch 'setup-improvements' of https://github.com/davidfischer/requests-ntlm into davidfischer-setup-improvements

Conflicts:
	setup.py
bumping version to upload ti pypi
Support stream=True when doing NTLM auth
bump version
Don't request the connection to be closed.

Not sending Connection:close means we can re-use the connection for multiple requests, reducing the amount of round trips needed for multiple requests.
Update README

Closes #23
Better error message if user omits domain from username
Typo in README.rst fixes #29
Changed relative import for python 3 compatibility.

I found that I could not use this package with python 3 due the following import error.

ImportError: cannot import name HttpNtlmAuth

This change allows it to be imported. I have not confirmed complete success with python 3 yet, this was the first step.
Support MS Exchange 2013 NTLM challenge

I have an MS Exchange 2013 server that likes to send this auth header as a challenge:

'www-authenticate': 'NTLM YadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYadaYada, Negotiate'

I'm not sure why MS chose to break the protocol, but anyway python-ntlm chokes on the superfluous "Negotiate" at the end, and removing it lets me communicate with the server.
Pick only the NTLM challenge from the auth cookie
Strip spaces around multiple cookie values

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html section 14.47 only mentions comma-separation, not comma+space separation. So split only by comma, but clean up any spaces afterwards.
In Python3, filter() is an iterator.
Fix for compatibility with requests-2.3.0
Fixes #38
Add whitespace for readability