Ned/merge lti hotfix

Add recovery command

Conflicts:
	common/lib/xmodule/xmodule/lti_module.py

Fixes to database columns

adds more temporary error messages

Hotfix/error msg ora panel

BLD-384: Add grading to LTI module

Co-author: Alexander Kryklia <kryklia@edx.org>
Co-author: Ned Batchelder <ned@edx.org>
Co-author: Oleg Marchev <oleg@edx.org>
Co-author: Valera Rozuvan <valera@edx.org>
Co-author: polesye
[BLD-384]

Co-author: Ned Batchelder <ned@edx.org>

This does not yet replace the existing per-student anonymous id, but
is intended to do so in the future.

Co-author: Alexander Kryklia <kryklia@edx.org>
Co-author: Ned Batchelder <ned@edx.org>
Co-author: Oleg Marchev <oleg@edx.org>
Co-author: Valera Rozuvan <valera@edx.org>
Co-author: polesye

Updates to depend on the latest version of XBlock, which includes
support for service-to-service (thirdparty) handler urls, which aren't
authenticated with a user (unlike handler requests coming from the
xblock client-side javascript).

Co-author: Ned Batchelder <ned@edx.org>

Fix LMS-1532 (partially instantiated XModules after an exception)

Fix for [LMS-1528], plus Changelog entry for the related feature

Also cleans up test_view_authentication to use user factories for
various user classes

Add release notes for 061a46be, concerning change to beta-tester groups

Sarina/dormsbee grades download

This guarantees that the ErrorModule will be created, instead of
potentially using a partially instatiated broken module. Fixes
[LMS-1532].

remove field_data_cache from grades.grade and grades.progress_summary

cleans grading code by adding wrappers

Ned/pr 1745 lms 1492

Webob represents uploaded files as cgi.FieldStorage objects.  The
XModule code expects pure Python file objects.  Each FieldStorage object
is wrapped to present the proper file interface, with file names.

LMS-1492

One test passes already, the other fails.  Fix in next commit.

These changes prepare for the changes to the tests that are coming, but
make no change to the behavior themselves.

Having ENABLE_S3_GRADE_DOWNLOADS enabled by default in common.py
could lead to surprising behavior for folks downstream. They'd
suddenly see a grade download screen on their new instructor
dashboard, but the links by default would be local files and
couldn't be used in an actual production environment. So we disable
by default and let people explicitly enable it and set it up for
S3 if they wish.

LMS-58

that are not present in a given student's gradeset.

General code cleanup and addition of comments.

Instructor dashboard API unit tests.

LMS-58

Restrict grade report generation to 'is_superuser' users (can be overridden with
feature flag ALLOW_COURSE_STAFF_GRADE_DOWNLOADS); all staff users can download
generated files.

LMS-58

Hook up display of grade files ready for download to new instructor dashboard.

LMS-58