(WIP) initial experiment for enabling accordion control for lms navigation.

[marcotuts]

Initial changes to enabling the navigation accordion control, presuming no configuration or settings necessary to merge this into the platform for now.

1.) IN PROGRESS - Expose collapsible navigation control
2.) Add in breadcrumb navigation above Unit page sequential allowing for clearer presence/location especially if user has navigation collapsed.
3.) When user clicks subsection in navigation sidebar, default (eventually) to collapsing sidebar once breadcrumb is in place.
4.) Visual cleanup to existing sequential bar and iconography used for accordion controls.

https://www.dropbox.com/s/oihhfxcan6qwe3e/Screenshot%202014-03-07%2005.17.15.png

via Hackathon 6. https://github.com/edx/edx-platform/wiki/Hackathon-Six%3A-New-Digs

[marcotuts]

Still To Do:

1. a11y - text in sr span,
2. transition --> animation/text/review,
3. font-awesome icon double caret left.
4. show text on hover

[singingwolfboy]

@marcotuts What do you want to do about this pull request? It's not helpful if it's just sitting here without any forward progress.

[marcotuts]

@shnayder - I'm going to go ahead and close this pull request for now, as it was mostly meant as a proof of concept and has been open/inactive for 2 months now. We can add this to the backlog, though if possible my recommendation would be to land this other pull request before the addition of this control. https://github.com/edx/edx-platform/pull/3096

thanks @singingwolfboy for the nudge on this. Stale PRs are stale PRs.