Speculative fix for before(:all) pending failures.

I'm not happy with this yet, but not sure a good way to do it :( There's some pollution of ivars going on that I don't like, and the naming is terrible.

Also what is expected behaviour if `pending` is called in `after(:all)` (failure or otherwise)? I thinking it should not even be defined at that time (or if it is, raise a "can't do that" error).

We should probably ship beta2 without this, since we're getting into pretty esoteric usage.

@JonRowe @myronmarston