Disabled automatic content filtering.

1. go to Website & Content → Browse Website
2. click on Content Mode tab
3. click on Edit Content button
4. in the opened Content Editor window press Source button
5. in the Content Editor window's textarea input test content <div class="bla-bla-bla">test</div>
6. in the Content Editor window press Source button twice - to switch to WYSIWYG mode and then back to HTML source mode
7. confirm, that test content is not changed, class="bla-bla-bla" attribute was not deleted automatically by Content Filtering subsystem