Unify password generation across FreeIPA
    
    Also had to recalculate entropy of the passwords as originally,
    probability of generating each character was 1/256, however the
    default probability of each character in the ipa_generate_password
    is 1/95 (1/94 for first and last character).
    
    https://fedorahosted.org/freeipa/ticket/5695
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Petr Spacek <pspacek@redhat.com>