Adapt transformed views to enable opt-in blocks transform

Requires https://github.com/plone/plone.app.blocks/pull/12
@gyst, @bloodbare 

So far, this is the only ugly part in making blocks transform opt-in: Calling main_template.macros must have a side effect of enabling transforms to enable them for all views with full layout.

Also, sometimes request does not have 'PUBLISHED' (e.g. on 404) and then we have to add something there to enable transform also for those views.