[EME] Spec converted to ReSpec

I just pushed a series of commits that convert the spec to use ReSpec. This
resolves bug 25506 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=25506>.
If you find issues (missing text, formatting, broken links, missing
references, etc.), let me know.

Thanks to Robin for the awesome tool and to Aaron for the JS framework he
built on top of it for MSE.

David