This all looks very impressive, I didn't get a chance to fully go through the code. I owe you a second review.

Here are some style issues that jumped at me during a quick overview though.

Yazan Medanat

Typo: Acknowledgements

An empty line or two would be nice here.

self._retried = self._lasturl == args[0]

self._retried = response.code == 401

return not cookie.is_expired()

Great work...too large to review all at once so I am just nitpicking a bit here...

remove the "," since it is a complete sentence

unreachable code? I don't think return True would get executed..

I've ignored some of the style things (e.g., one-line summaries) since this is prototype code.

This is more out of curiosity, but what is self.retried used for? I was looking at http://code.reddit.com/docs/urllib2-pysrc.html and it doesn't seem to mention it in the parents (though I suppose it doesn't preclude usage elsewhere).

Is there a reason this is separate initialization call here?

Should the '1.5.2' bit be pulled out into an explanatory constant?

Should this return False here or raise an exception? The return value seems to be ignored anyway.

Does this still need to be handled?

Will this method ever reach the end? Does it matter what it returns?

Does this need to be a class variable?

Would it be cleaner to set these values all at once?

Would this be better off being done using HTTPError? http://www.tornadoweb.org/documentation/web.html#everything-else