fix exception in LMS when rendering newly create multiple choice problem...

fix exception in LMS when rendering newly create multiple choice problems. The capa module is barfing on the HTML comment which was in there and the XML parser couldn't handle it.

Fix/cdodge/cas bugs

Conflicts:
	cms/templates/widgets/header.html

Fix/cale/edge bugs

Conflicts:
	cms/static/js/base.js

save_item should also do proper 'is this element draft aware' logic so that incorrect versioning occurs on elements which do not support versioning at this point in time (aka courses, sections, and subsections).

Feature/cdodge/cas new course

swallow exceptions when generating thumbnails

Merge branch 'feature/cale/cms-master' of github.com:MITx/mitx into fix/cdodge/cas-thumbnail-exception-handling

Feature/cale/cas import ui

removed red import button – drawing too much attention; this will be reworked onto a different page at some point anyways

styled edge registration form

DraftMongoContentStore needs to both delete the draft *and* the non-draf...