2) forbid exam for students with <38

Page "edit discipline > students".

1) Incorrect students list
2) problems with output file.

Conflicts:
	~dev_rating/application/classes/Controller/Handler/FileCreator.php
	~dev_rating/modules/account/classes/Model/Kohana/Account.php

Conflicts:
	db/fix.sql
	~dev_rating/application/classes/Controller/Handler/FileCreator.php

Use $user or User::instance() instead

Reduced usages of UserInfo