Asynchronous API for 2.0

[gregrluck]

This is a placeholder issue for the work being done to add an async API for 1.1

Create a behaviour table in spec and also examples to explain interactions.

[gregrluck]

We are moving this to a branch which will be labelled asyncapiproposal. We are marking it for 2.0 which will require a new JSR.

[gregrluck]

This is too big to do in JSR107 so closing.