Reorganize information in CONTRIBUTING.rst, link to ReadTheDocs
wordsmithing
When sending bulk email check if course is authorized.
Also the idash_mode property is stored seperately for each course.

LMS-2565
Remove email field from CS client user object

This requires cs_comments_service commit 1d50176.
Do not show "View in Studio" links for child verticals of verticals.

STUD-1558
Show error page templates
Drag and drop on container page.

STUD-1309
dnd container page styling
Switch the container page to use the new view
Restore the ability to drag at any level inside a vertical and clean up templates.
Update unit test based on changes in master.
fix authentication check in auth
add logging to course import
pep8/pylint cleanup
fix for Studio 404 and 500 page layouts
STUD-864
Only show drag handles in draft mode
Bok choy acceptance test for drag and drop.
Allow for no runtime_type in the context.
Fix Jasmine tests

Also, rewrite them to be easier to comprehend, and to not use magic constants (or to use fewer, at least).
Clean up coverage and code quality issues