CLC-3811 Test for Google leakage in view-as

https://jira.ets.berkeley.edu/jira/browse/CLC-3811

It's important that we not leak Google data to view-as users when a real-user's feed is cached. But currently our automated protection consists of one RAILS_ENV=testext test. This PR adds tests for each feed at the controller level.
Good call to make this its own class.