LMS-2936

Also, a bunch of ancillary cleanups.

Conflicts:
	common/lib/xmodule/xmodule/modulestore/tests/test_publish.py

Conflicts:
	cms/djangoapps/contentstore/management/commands/migrate_to_split.py
	cms/djangoapps/contentstore/management/commands/tests/test_rollback_split_course.py
	common/lib/xmodule/xmodule/modulestore/__init__.py
	common/lib/xmodule/xmodule/modulestore/mixed.py
	common/lib/xmodule/xmodule/modulestore/mongo/draft.py
	common/lib/xmodule/xmodule/modulestore/split_migrator.py
	common/lib/xmodule/xmodule/modulestore/split_mongo/split.py
	common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
	common/lib/xmodule/xmodule/modulestore/tests/test_split_w_old_mongo.py

Bug/stud 1962

Testing for bugs off master for opaque-keys deprecation
LMS-2753

Pull out edX into variables in password reset email

Fix opaque key TODOs left over from split-migrator changes and fixed test_image_import to use the correct course

Reset get_location_from_path to pre deprecated opaque-keys

Fix CMS acceptance test

Fixed usage key reassignment in item.py

Remove unnecessary check.
Fix merge conflict

Add filter to only show first occurance of DepWarning

Handle unicode in get_course_index

Since we're trying to get rid of location mapper,
skip these tests until we get rid of it entirely.

Setting default system to be lms in unittests

Defensively checks that children exist in has_changes

Disable failing video language test

Added discussion label change to release notes

New "Active Students" data on instructor dash

Subsume browser links to variables, to exclude from translation

Show thread user to staff when only anonymous_to_peers is true

FOR-122

unicode fixes