Merge pull request #2899 from edx/alex/multiple_transcripts_editor

CHANGELOG.rst

cms/djangoapps/contentstore/features/common.py

...ontentstore/features/component_settings_editor_helpers.py

cms/djangoapps/contentstore/features/textbooks.py

cms/djangoapps/contentstore/features/transcripts.feature

cms/djangoapps/contentstore/features/transcripts.py

cms/djangoapps/contentstore/features/video-editor.feature

cms/djangoapps/contentstore/features/video-editor.py

cms/djangoapps/contentstore/tests/test_transcripts_utils.py

cms/djangoapps/contentstore/views/tests/test_transcripts.py

cms/djangoapps/contentstore/views/transcripts_ajax.py

cms/static/coffee/spec/main.coffee

cms/static/coffee/spec/main_squire.coffee

cms/static/coffee/spec/models/upload_spec.coffee

cms/static/coffee/spec/views/upload_spec.coffee

cms/static/js/models/uploads.js

cms/static/js/spec/video/transcripts/editor_spec.js

cms/static/js/spec/video/transcripts/file_uploader_spec.js

cms/static/js/spec/video/transcripts/message_manager_spec.js

cms/static/js/spec/video/transcripts/utils_spec.js