Merge pull request #12278 from edx/christina/cohort-messages

lms/djangoapps/instructor/views/instructor_dashboard.py

lms/djangoapps/verified_track_content/tests/test_views.py

lms/djangoapps/verified_track_content/views.py

lms/static/js/groups/models/cohort.js

lms/static/js/groups/models/verified_track_settings.js

lms/static/js/groups/views/cohorts.js

lms/static/js/groups/views/cohorts_dashboard_factory.js

...c/js/groups/views/verified_track_settings_notification.js

lms/static/js/spec/groups/views/cohorts_spec.js

lms/static/sass/base/_variables.scss

lms/static/sass/course/instructor/_instructor_2.scss

.../instructor/instructor_dashboard_2/cohort-form.underscore

.../instructor/instructor_dashboard_2/cohort_management.html

lms/urls.py