Altered annotation behaviour of search results.
Altered annotation behaviour of search results.

Previously this was done implicitly in the SearchQuerySet.iterator() method,
which Django would call internally when evaluating the queryset.

Django 1.11 changed its behaviour to use a ModelIterator class instead of
just calling `iterator()` on the queryset. Rather than suppy a custom
ModelIterator, we just make the annotate explicit.

wbtuomela/mezzanine,dsanders11/mezzanine,christianwgd/mezzanine,jerivas/mezzanine,molokov/mezzanine,readevalprint/mezzanine,frankier/mezzanine,stephenmcd/mezzanine,jerivas/mezzanine,wbtuomela/mezzanine,wbtuomela/mezzanine,frankier/mezzanine,molokov/mezzanine,dsanders11/mezzanine,jerivas/mezzanine,frankier/mezzanine,christianwgd/mezzanine,readevalprint/mezzanine,stephenmcd/mezzanine,readevalprint/mezzanine,molokov/mezzanine,stephenmcd/mezzanine,christianwgd/mezzanine,dsanders11/mezzanine