Move spec to project repo

[jugglinmike]

If the specification were hosted in the project repository (as opposed to the wiki), discussion could occur through issues and pull requests, and they could reference specific line numbers.

[jrburke]

This should be done now, and I sent a message to the amd-implement group here:

https://groups.google.com/forum/#!topic/amd-implement/6Y-UChTpmP4