[web2py] Auth module requirements

[david.waldrop]

Currently the auth systems requires the user to enter first name and
last name.  Is there a way to turn this off.  I see in the Reddit
example these fields are replaced by "alias", but note in the book
that the fields are required to be in the table.  Ideally I want the
user to only enter an alias (as a string so they could enter an email
as a alias) and a password.  I do not see how to do this given the
requirements on the alternate auth_user tables structures.