Merge remote-tracking branch 'remotes/upstream/master' into tests_for_#376

accounts/migrations/0003_user_schema_migration.py

course/admin.py

course/auth.py

course/content.py

course/flow.py

course/grading.py

...tions/0107_rename_flowpagedata_ordinal_to_page_ordinal.py

course/migrations/0108_alter_page_ordinal_verbose_name.py

...ations/0109_add_manage_authentication_tokens_permssion.py

course/models.py

course/page/code.py

course/page/code_runpy_backend.py

course/page/text.py

course/templates/course/flow-confirm-completion.html

course/templates/course/flow-page.html

course/templates/course/grade-flow-page.html

course/templates/course/gradebook-single.html

course/utils.py

course/versioning.py

course/views.py