Fix list editor tests.

Sort of.  The editors need to be rethought to take into account the
namebiguity.
There's no more type attribute on Video.
This rescue_from seems really ill-conceived.  Solution: deletion.

I likely didn't have a good reason to install it.
Eliminate rbx-lock.

I wish there was a way to say "we support two Ruby environments", but
that doesn't seem to be in Bundler 1.3.0.
Bah, forget it.  Taking the plunge.
I am now of the opinion that these unit tests will never pass.

The videos/new population behavior, if it gets complex enough to warrant
tests, will likely just need to be covered by integration tests and/or
factoring out the complex stuff into something more testable than an
Ember controller.