feed es view (bug 1036216)

Breaking https://github.com/mozilla/zamboni/pull/2298 up.

- Do a filter on FeedItem by region that puts matching region/carrier operator shelves on top.
- Do an OR query for FeedApp/Brand/Collection/Shelf using IDs
- Do an OR query for apps using IDs

Relies on [indexers](https://github.com/mozilla/zamboni/pull/2314) and [serializers](https://github.com/mozilla/zamboni/pull/2313).
If region only is passed, it returns a query like `{'function_score': {'filter': {'bool': {'must': [{'term': {'region': 'us'}}]}}}}` but there's no `function` for the `function_score`?