Add ability for users to change their password when updating their profile.


* If user is guest AND $emailasusername is TRUE then show password
fields. This allows new users to create a password
* If we are on the userinfo page AND $emailasusername is TRUE then show
password fields. We have a logged in user and changing profile.
* If user is not a guest AND the view is not userinfo then the user may
be registering for another subscription and we do not need them to
update their password on this screen.