LMS-11177 Add Split to configuration settings.
LMS-11179 Fix Assets with Split
Add feature flag to create Split Course (part of LMS-11019)
Make default_store thread-safe.

Conflicts:
	common/lib/xmodule/xmodule/modulestore/mixed.py
Fix creating and finding courses + review comments.
fixup assets.
LMS-11168 Support for removing versions in Split, Mixed, and SQL.
removing rake and  outdated references to it
rebased with master
more js
enabled re-run button on My Courses page
Studio: adding course re-run-centric static template rendering

* initial HTML for dashboard states
* initial HTML for new course re-run view/form
* initial HTML placeholder for outline alert UI

Conflicts:
	cms/templates/index.html
Studio: adding styling for course re-run-centric views

* adding new view/page mast-wizard type
* refactoring create course/element form styling
* adding course re-run view specific styling
* adding courses processing styling (w/ alerts and status)
Course rerun server-side updates: support display_name and DuplicateCourseError.
Fixed templates
cleaned some things up
Studio: further design revisions and tweaks from feedback

* removing new window attribute from re-run control
* removing links from processing courses
* revising look/feel of dismiss action on dashboard + alert
* correcting font-weight of dashboard processing title
* adding extra space to course rerun action on dashboard
* re-wording secondary cancel action on rerun view

Conflicts:
	cms/templates/index.html
Added interation on unsucceeded courses in dashboard
fixes
Minor changes