Feature/tomg/cms library

add a 'safety switch' where we add new content into GridFS with a filena...

Feature/cale/cas component delete

Hook up the component delete button to the backend. Don't break if the process of updating a parent unit after deleting is interrupted (leaving a pointer to a missing module)

Enable reordering on the unit page

Feature/cdodge/subsection edit page

add subsection edit page to the project with a shared 'unit' widget that will render out unit lists. Both edit_subsection and overview.html will share this widget

add subsection edit page to the project with a shared 'unit' widget that will render out unit lists. Both edit_subsection and overview.html will share this widget

Merge branch 'feature/cale/cms-master' of github.com:MITx/mitx into feature/cdodge/subsection-edit-page

add a 'safety switch' where we add new content into GridFS with a filename (which GridFS maintains an index on) in case any assumptions about our new id scheme proves to be false. We can query by filename (which is a /tag/org/course/category/name format) so it'll be unique

code mirror styling and a few small tweaks

Feature/cdodge/asset id change

for get_all_content_info_for_course(), return a list of the MongoDB query rather than a cursor object. Also add some documentation (in a comment) as to what a caller should expect

use better encapsulation for the naming convention behind thumbnails. Put it all in content.py rather than view.py.

refactor StaticContent id scheme to be the same as moduledata. Also expose a new 'get all content for course' which will be needed to support a asset management page.

allow 'is_staff' flagged user accounts to run as super-admin, which mean...