Merge pull request #2927 from edx/adam/allow_usernames_or_email

make widget accept usernames or emails (LMS-1438)
Merge pull request #2857 from edx/adam/new-data-download

Update data download dash for parity (LMS-1203)
Allow uppercase transcripts srt extension.
Added internal refs to help researchers find the data format files
Merge pull request #2930 from edx/ahodges/documentation/updateindex

Added internal refs to help researchers find the data format files
Minor code cleanup.
Improve text referencing link for translators.
Don't translate reference code.
Merge pull request #2924 from edx/andya/studio-split-test-support-2

Fix split_test xblock so that it can render in Studio
Merge pull request #2931 from edx/alex/allow_uppercase_srt_extension

Allow uppercase transcripts srt extension.
Merge pull request #2838 from edx/andya/container-publishing

Support publishing of nested xblocks
Merge pull request #2923 from lduarte1991/master

CSS changes regarding TinyMCE in annotation tool & accessibility issues
Remove coursename from page H1, and slightly improve sequence navigation
Make i18n tests quieter
pep8
Merge pull request #2654 from pdehaye/patch-1

missed rst
Fixed confusing docstring
Merge pull request #2936 from edx/flowerhack/dark-lang-docs

Fixed confusing docstring
Consolidate information from data.edx.org, Appendix E, and problem types
Improve dump_course_ids test for unicode course_ids