Pre-auth actions should not be taken when users can't set their own password

currently, LT ties the pre-auth/validation functionality to the ability of users to set their own password. some of the code tests to determine if the user was in the pre-auth role failed to test if the site was even set up to allow users to set their own password. attached patch to correct the problem has been committed to HEAD and 6.x-1.x, and a related patch has been applied to 5.x-1.x.