CB-5739 windows8

Separate branch for revised Windows 8 Platform Guide. Unresolved issues:

* The CLI's run/emulate commands don't work in Win8, though there's no problem getting the corresponding features to work within the SDK, as doc'ed here. Is this a bug?

* Doc assumes the same version of Windows as required for WP dev: 64-bit Pro. Correct? If not, suggest it as a recommendation to match WP dev.

* Requirements assume various 2013 VS releases. I didn't test each ii isolation, and not sure how the various editions differ. I succeeded after installing the Ultimate SDK. Prior to that, confirmed you can't rely on the WP SDK to match that dev track.