Async working group

[nikomatsakis]

Metadata
Name	Async Foundations Umbrella Initiative
Owner	@nikomatsakis, @tmandry
Lang team liaison	TBD

Purpose

The async foundations umbrella initiative is encouraging the development of a robust, asynchronous networking ecosystem for Rust. This initiative includes language features (e.g., async-await), new libraries (e.g., traits for portability and interop), and potentially tooling as well.