Update test blueprints to new format

[Gorzas]

I was working lately with ember-light-table and version 3.24 of Ember. I've found that, when creating a new cell-type, it also creates an integration test file but it's in the old format. I think we should update it using the lately integration tests of Ember.

I'll open a PR as soon as possible so you can see an example of what I'm talking about.

[Gorzas]

If somebody could take a look to the changes, I can actually update the rest of the blueprints :).

[Gorzas]

Thanks @rwwagner90 for the merge! I'll close this ticket if no more work is needed 😄