Fix tests broken in e708c07

r? @robhudson @ngokevin

Broken build: https://travis-ci.org/mozilla/zamboni/builds/32461408

I'll let Travis finish before merging even after an r+, but these both pass, so I'm feeling good about it:

- `mkt/feed/tests/test_serializers.py:TestFeedCollectionESSerializer.test_home_serializer_listing_coll`
- `mkt/feed/tests/test_views.py:TestFeedView.test_200`