fix isEmpty method for file validator.
Update FileValidator.php

fix tabs
Update FakedValidationModel.php
Update FileValidatorTest.php

fix tabs
Update CHANGELOG.md

updated changelog about isEmpty bug.
Update CHANGELOG.md
Merge branch 'fix_is_empty_file_validator' of github.com:ZhandosKz/yii2 into ZhandosKz-fix_is_empty_file_validator

Conflicts:
	framework/CHANGELOG.md