Hide Markdown layout-mandated HRs
Deprecate need for Markdown include for slide

Replace any Markdown and `{% include %}` with jQuery `wrapAll` and use
of HRs and delineation.
Add example (temporary) of new Markdown slides
Ported all Foundations content to example
Simplify JS for slide-building
Correct Markdown resulting in diagram as H2
Convert all decks to new slide via Markdown only
Remove deprecated slide deck includes
Update README to match current document state
Remove deprecated include uses
Bring up-to-date with content changes on origin/master

Merge remote-tracking branch 'origin/master' into no-more-includes-for-slides
Resolved "Platform Survey" content order for "Teams" and "Organizations" slides

Conflicts:
	foundations/index.md
Merge pull request #287 from github/no-more-includes-for-slides

Deprecate `include` for all slide panels in decks