Move tests related to views files into views/tests.

@singingwolfboy Can you review this cleanup PR? I was adding a new test for a file in contentstore.views, and I was annoyed that the tests for those files live in contentstore.tests instead of contentstore.views.tests. So I decided to move the existing tests (at least the ones that obviously map to a file in contentstore.views).

I also did some pep8 cleanup.