Handle metadata from save being empty

Decrease the number of queries needed for LMS courseware

Cheat sheet for heading and explanation.

explanation markdown

Add BDD lettuce tests for studio overview toggle section feature.

the parent directory might not already exist, so we have to call makedir...

the parent directory might not already exist, so we have to call makedir with recursive=true to auto-create any parent folders

Catch ItemNotFound errors at the top of get_module, rather than in get_module_for_descriptor, to maintain previous LMS behavior

Feature/cas/speed editor

This cuts the number of queries in 6.002 courseware loads from ~650 to
~5-40. Still to do: cache CustomTag templates so that we only load them
once per request.

make sure we commit the course module first when importing. There's a sn...

Moving Static Component View Under Modal While Editing

make sure we commit the course module first when importing. There's a sneaky little ordering dependency where we can't save a static tabe until the course module has been saved. This is because - when saving a static tab - we have to scribble on the course module's metadata to point to it.

update timepicker to fix minutes bug

Course Overview Section Collapse/Expand Toggling

fixed it

Feature/cas/speed editor

Fixed time picker race condition for grace period. Still quirky in that

in rounds down times from :01-:09 to :00 (and perhaps others). I think
that's a bug or setting in timepicker.

change over the 'get all discussion models' to use get_items() which is ...