Password required mark logic change

Currently Password and VerifyPassword fields are not marked as required. This results in missing asterisk ("*" - required mark) on new user add form (in administrative console and on front-end). Then when value is set to the field, kPasswordFormatter class makes them required for new users. This gives us another problem - inability to dynamically make password non-required for new users.

I propose to remove "making required" code from kPasswordFormatter class and do the following:

1. in u:OnPreCreate (for administrative console) and in u:OnNew (for front-end) events do $object->setRequired for both password fields - helps to initially show "*" on user registration form;
2. in u:OnBeforeItemCreate do the same - to make passwords required when user is saved to database.

This way it will be highly customizable and more transparent logic to the naked eye.