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 mget is that simple you don't need a helper method:
```
apps = es.mget(body={'ids': apps}, index=WebappIndexer.get_index(), doc_type=WebappIndexer.get_mapping_type_name())
```