Moved placeholder logic out of Javascript and the DOM

and into CSS
Removed cnxmlplus handler
Moved title out of the type-container element
type-container is removed from the serialized DOM
For new math, drop the plain text option.

This fixes #420.

Conflicts:

	src/plugins/oer/math/lib/math-plugin.coffee
	src/plugins/oer/math/lib/math-plugin.js
Merge branch 'master' into placeholder-in-css
Renamed variable
Notes with textnode children will get a para
fix typo in semanticBlock makeClean
fix images and exercises
add note type if it doesn't exist
Set minimum height of table cell so they don't collapse if the cells are empty.
Add the preview classes to ephemera

This removes these classes if the editor decides to save while you're hovering
over one of the add column/row menu items.
show block controlls when query variable is present
remove console log in oer/index
bugfixes to exercise plugin
fix bug in note title handling
Merge branch 'master' into placeholder-in-css
fix type selection for notes
Merge pull request #16 from oerpub/oerpub-ticket424-pull

Oerpub ticket424 pull