Also fixes STUD-1351

Fix case where both old and new transcripts are uploaded, but transcript language isn't one of the new transcripts.

LMS-1479

This information will likely be used frequently for analytics purposes, so we would like to denormalize here to avoid having to join with the modulestore later.

Fixes: AN-594

add dummy strings

To get all dates localized, we need all runtimes to have the i18n
service, and since runtimes are made by the modulestores, we need to
pass it to them.

Soon (fingers crossed), modulestores won't be involved in making
runtimes, and many of these changes will go away.

This requires fixing the javascript api implementation, and adding
an implementation of get_block to the ModuleSystem api.

However, the implementation is incomplete, due to mismatches between
the expectations of XModule and XBlock.

Also adds tests using the Acid block to make sure that the javascript
and python apis for children are working correctly.

make openendedchild and open_ended_module_v1 act enough like xblocks to get xblock 18n

Added feature setting 'DISPLAY_HISTOGRAMS_TO_STAFF' to configure display of histograms in Staff Debug Info panel.

Generating histograms requires scanning the courseware_studentmodule table on
each view. This can make staff access to courseware very slow on large courses.

Default is False.

LMS-1199

Renamed feature setting 'DISPLAY_HISTOGRAMS_TO_STAFF' to 'DISPLAY_DEBUG_INFO_TO_STAFF' to better communicate its purpose.

Default is True.

LMS-1199

STUD-1151

Student logins to edx, plays video, selects position, closes
browser, opens video, position is restored.

BLD-385

screen readers. Also, the mathjax message should be wrapped to prevent
non-IE browsers from complaining about a feature that is IE-only.

[LMS-179]
[LMS-209]
[LMS-1345]

Removed inappropriate section tags. Because screen readers announce each section, they should not be used unless they are actually defining meaningful sections.