Merge pull request #4377 from edx/ned/fix-pr-4168

unicode fixes
Subsume browser links to variables, to exclude from translation
Show thread user to staff when only anonymous_to_peers is true
FOR-122
Merge pull request #4297 from mlkwaqas/waqas/for122-anonymous-post-are-anonymous-to-staff

Show thread user to staff when only anonymous_to_peers is true
Merge pull request #4379 from Stanford-Online/kluo/exclude-browser-translation

Subsume browser links to variables, to exclude from translation
New "Active Students" data on instructor dash
Merge pull request #4376 from edx/ahodges/documentation/activestudents

New "Active Students" data on instructor dash
Added discussion label change to release notes
Merge pull request #4387 from edx/markhoeber/documentation/doc-748

Added discussion label change to release notes
Defensively checks that children exist in has_changes
Disable failing video language test
Merge pull request #4393 from edx/zoldak/disable-video-lang-test

Disable failing video language test
setting default system to be lms
Merge pull request #4390 from edx/benmcmorran/defensive-has-changes

Defensively checks that children exist in has_changes
Pull out edX into variables in password reset email
Merge pull request #4395 from edx/mvo/unittests_alone

Setting default system to be lms in unittests
Testing for bugs off master for opaque-keys deprecation
Fixed some isinstance errors with opaque-keys
Removed some definition_key references
Switch offering to course and run