import aq_acquire method instead of trying to get it from the view

This PR changes the full feed view to use the imported aq_acquire method instead of acquiring it from the view. This fixes an issue where self.aq_acquire is not available.

Not sure in what cases this could happen, it might be related to my Plone (3.3.4) set up, but AFAIK there is no harm if we use the aq_acquire import instead of self.aq_acquire.

I also did some code cleanup (pep8) and reorganized imports.