Added markdown icon and menu components
Disables the markdown menu item if markdown isn't support on the current slide
Merge branch 'master' into markdown

Conflicts:
	app/bundles/app/strut.slide_editor/view/OperatingTable.js
Layed out the code path for the markdown mode.
Using a single codemirror isntance for markdown support.

Why a single instance?  I don't trust codemirror's cleanup.
Added codemirror and required modes
Brings up codemirror for markdown editing
Added little tabs to allow switching between markdown and preview modes
Saves the markdown values
Added the "marked" markdown parser

https://github.com/chjj/marked

Support tables, reasonably light weight and claims to be fast.
Basic markdown support.  Needs styling...
Renders markdown in presentation
Restored reveal.js css.  Need to reconcile the styles between all editors
Merge branch 'master' into markdown
de-conflicting CSS betweent Strut and the various presentation backends
Silly way of getting reveal themes into the markdown area

Need to just re-work the stylesheets to apply the styles
only to ".themed-content"
Merge branch 'master' into markdown
Uses `.themedArea` instead of `.reveal .slides > section`
Commits markdown changes when changing active slide or clicking present
Added reveal themes to other presentation backends