page: Simplify bemhtml to save modes from page on page__body. Closes #516

Fix touch template regression
Refer: https://github.com/bem/bem-core/commit/789125c086dd73e58973593826a2518b9be97fb5
Merge pull request #542 from bem/issues/516-2@v2

page: Simplify template to save modes on page__body. Closes #516