TNL-922

Move lms.lib.xblock into lms.djangoapps.lms_xblock in preparation add database backed configuration to it

Fixed the edX middleware to lazily create request
context for Mako templates, so that it is based on
any changes made to the request object.

Verified that with this fix the "Instructor" tab is
correctly hidden when a staff member is viewing
the course as a student.

Move modulestore config for tests to an importable location
Disable pylnt warning for lms imports in common tests
Refactor all testcases that loaded all xml courses
TE-610
TE-489

also fix other users of check_mongo_calls to use None if they don't care about sends
PLAT-239

[PLAT-191]

LMS-11366

Conflicts:
	cms/djangoapps/contentstore/tests/test_import.py
	common/lib/xmodule/xmodule/modulestore/__init__.py
	common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
	lms/djangoapps/courseware/tests/test_module_render.py

[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.

Included adding a general create_toy_course and create_sample_course method for tests

[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]

STUD-1558

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

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.

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