Uses JS terms for the result of pending()

It's really weird to say that `pending()` should return a Tuple
in JavaScript. The language has no concepts of Tuples, and when
you say "it should return a Tuple of `{ promise, fulfill, reject }`"
I immediately think about a Haskell Tuple, which would be
`( promise, fulfill, reject )`, and close to the JS idiom
`[ promise, fulfill, reject ]`.

This, as it turns out, is quite unintuitive for people who
are used to the concept of tuples (and working with them in
other languages like Haskell or Python), who will have their
`pending` function return such List, just to find out quite
a while afterwards that you should actually be returning an
Object, as I've discovered from reading @briancavalier's avow tests
(https://github.com/briancavalier/avow/blob/master/test/avow-adapter.js#L4-L11)