Accept all formats of new-style connection hints

The general parsing code for endpoint strings and the specific parsing code for
TCP client endpoint strings has been copied from Twisted, because there is no
public API for parsing or generating endpoint strings. It will be removed after
the switch to endpoints.

Source: https://github.com/twisted/twisted
Git commit: c139e22c7abc705114fd4f0e8afde8364e06f918
deprecate UnauthenticatedTub, prep for removal in 0.8.0

refs ticket:67
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