Timing of availablechange event to signal screen availability

[markafoltz]

From http://webscreens.github.io/presentation-api/#example:

Do we want to fire an event immediately after the page registers for it? What's a best practice method for asynchronous notifications of ths kind?

[markafoltz]

This can be addressed by a small modification to the existing algorithm for onavailablechange. If we fire an availablechange event to any handler that is added (regardless of the status of the screen list) then we should be good.

[schien]

This issue can be addressed by the API modification introduced in #81.

[markafoltz]

As we have implemented a Promise-based API for retrieving the availability status, I believe that this issue has been addressed.