Preparing Final Report

* Created a snapshot of the current discussion, taken from https://www.w3.org/community/webscreens/wiki/API_Discussion and mailing list input
* This snapshot of a discussion is pending definition of API semantics, serves as a starting point and input to the working group
* Moved old version to its own page, changing the licensing to CLA
* Created new Final report, status as Final report under Final Report Agreement