use django-browserid

Conflicts:
	lists/templates/base.html
Revert "use django-browserid"

This reverts commit 92e2799eb06af82575fda0134c7425eaeb1c449c.
spiked implementation of persona

Conflicts:
	lists/templates/base.html
	superlists/settings.py
a few more tweaks to the spike, incl the admin view.