Port "old" API tests for content views

Make module `test_contentview_v2` accomplish most of what module
`test_contentview` formerly accomplished. Module `test_contentview` is still in
place:

* Not all tests in that module have been implemented, so they are untouched.
* Some tests in this module do not test content views, so they should be ported
  into somewhere other than `test_contentview_v2`.
Our codebase makes use of both `ddt.data` and `decorators.data`. Importing `ddt` and `decorators` makes all usages of the decorators very unambiguous. When I read code and I see this:

    @data

I have no idea if we're using our custom decorator or the vanilla decorator without hopping to the top of the module. On the other hand, this is unambiguous:

    @decorators.data
    @ddt.data

So - I'm typing out more verbose decorator names in order to reduce the amount of reading I have to do at a later point.