Merge remote-tracking branch 'edx/master' into opaque-keys-merge-master

common/lib/xmodule/xmodule/modulestore/xml_importer.py

common/lib/xmodule/xmodule/video_module/video_handlers.py

docs/en_us/course_authors/source/Format Cheat Sheet.rstnouse

docs/en_us/data/source/index.rst

docs/en_us/data/source/internal_data_formats/event_list.rst

...en_us/data/source/internal_data_formats/tracking_logs.rst

lms/djangoapps/courseware/tests/test_video_handlers.py

scripts/show_events.py