Replace async

[hueniverse]

New policy doesn't allow using non 1.x modules, unmaintained modules, or modules with such dependencies.

[cjihrig]

Is the plan to fork Async, or create something new?

[Marsup]

Considering async is mainly used for forEach/forEachSeries in the project, would it be crazy to suggest transforming it to a promise-based implementation ?

[hueniverse]

@cjihrig I can implement what I need in a tiny little utility function.
@Marsup yes, crazy.