[STUD-2903]

LTI grade callbacks for example, come in with an anonymous user.  This causes a
stack trace in the psychometrics app that leads to the LTI service
getting a 404.  This adds a check before that callback gets registered.

LMS-2737

[LMS-2757]

This commit updates lms/djangoapps/courseware.

These keys are now objects with a limited interface, and the particular
internal representation is managed by the data storage layer (the
modulestore).

For the LMS, there should be no outward-facing changes to the system.
The keys are, for now, a change to internal representation only. For
Studio, the new serialized form of the keys is used in urls, to allow
for further migration in the future.

Co-Author: Andy Armstrong <andya@edx.org>
Co-Author: Christina Roberts <christina@edx.org>
Co-Author: David Baumgold <db@edx.org>
Co-Author: Diana Huang <dkh@edx.org>
Co-Author: Don Mitchell <dmitchell@edx.org>
Co-Author: Julia Hansbrough <julia@edx.org>
Co-Author: Nimisha Asthagiri <nasthagiri@edx.org>
Co-Author: Sarina Canelake <sarina@edx.org>

[LMS-2370]

XBlocks can and should use the "publish" method provided by the runtime to emit analytical events. In theory we could now start replacing calls to track_function with calls to publish, however, that migration is not handled by this change.

Fixes: AN-789

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

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.

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

Default is True.

LMS-1199

Make XBlock client-side runtimes proper classes, so that handlerUrl can
be defined in a per-runtime way, and we can have multiple runtimes on a
single page.

[LMS-1630][LMS-1421][LMS-1517]

fixing unit tests

fixing merge error

fixing xqueue submission issue with unicode url (trial 0.1)

fixing fotmats as commented upon

removing yaml file language selection

Unicode changes to support QRF

removed unnecessary pass in modulestore/init.py

fixing merge error

fixing fotmats as commented upon

removing yaml file language selection

fixing pep8 violations

- fixing pylint violations

pylint violation

fixing line spaces and formats

ignore pylint E1101

remove empty line

fixing pylint violations

 pep8 violations

bulk mail unicode/decode

fix migration error

fix pep8 just to push again

more unicode/decode
Final changes to comments and error messages.

XModules continue to use their own interface for xml, but provide an
adaptor that makes the the XBlock interface available.

[LMS-179]

Adds a feature to the edX platform which allows instructors to set
individual due dates for students on particular coursework. This code is
meant primarily for on-campus use--it is not intended that this feature
would be used for MOOCs. It adds a new tab, "Extensions", to the beta
instructor dashboard which allows changing due dates per student. This
feature is enabled by setting FEATURES['INDIVIDUAL_DUE_DATES'] = True.

[LMS-226]
[LMS-2013]

The django.utils.translation module has the right interface to serve as a
gettext.Translations object, so we use it for the runtime i18n service.

LMS-1597