[Zope-PAS] Cookie authentication and stuff

[Lennart Regebro]

Tinos solution seems to work. I have replaced the traversing with a 
slightly more complex traversing that is know to work safely (it's used 
by getLocalRoles and stuff) and added the challenge request.

This will typically end by a
	raise 'Redirect', url
to redirect to the correct page.

I'm currently working on a Yale CAS plugin to test this whole thing, and 
it seems to work. I can add the CASAuthHelper.py into the Zope CVS if 
you want to. It is a very good single sign-on system, something that 
seems to be quite in demand...


Oh, and I added logs for all the swallowed plugin-exceptions so that and 
administrator will have a chance to see why his plugins doesn't work, 
and fixed a minor bug.

//Lennart