Version 2.0 [was documented to use bluebird if installed](https://github.com/normalize/mz/tree/2.0.0). The switch to `any-promise` 1.0 in 71ad960e0d02d32f512d68904b53ad4af9797f95 changed that and now the builtin `Promise` is used. Shouldn't `mz` now be at `3.0`?