remove some code that has to do with unauth

I don't know what this code does, but it has something to do with
unauthenticated mode, and removing it doesn't break any tests.
remove all mention of Unauthenticated mode

This patch breaks unit tests.
fix tests
negotiate.py: fix one last conversion question
cosmetic: wrap code now that lines are shorter
fix some pyflakes complaints

and a function that should have made pyflakes-0.8.1 complain, but it has
a bug and doesn't always notice shadowing in list comprehensions
remove GoodEnoughTub

It was a testing tool that used a real Tub if crypto was available, else
it used an UnauthenticatedTub. Now that crypto is always required, rip
this out.
Remove UnauthenticatedTub

Closes ticket:67.