[PROD-1287] - Add logs to optimized ProblemGradeReport code.

Django2: Update django-model-utils

Update this library in order to get the Django2 fix in https://github.com/jazzband/django-model-utils/pull/335

 Add teamset type validation to has_specific_team_access

BOM-1428: Fix Django 2.0 test failures in theming management command

LEARNER-2041: Remove deprecated LogoutViewConfiguration from student models

We'll upgrade this again along with pytest once pytest-dev/pytest#6925 is resolved.

Also, it looks like a flaky error in test class DB setup outside a transaction was mucking things up for the rest of the test shard. I didn't try to fix the flakiness, but this should at least limit the blast radius to just that test class. We really need to start using setUpTestData() more consistently.

Django2 CMSH Router: add clarifying comment

Django2 CSMH: Database Router update

Make XBlock views/handlers non-atomic requests.

Updated ORA2 version

Fixes test of email body for Django 2.0.

[PROD-1287] - Remove flaky test lms.djangoapps.instructor_task.tests.test_tasks_helper.TestProblemGradeReport.test_grading_failure

BOM-1438

Fix course_id string.

fixed tag issue

We're seeing slow commits on production for courseware_studentmodule
updates. Based on the slow queries during those times, we think it
might be because multiple worker processes are trying to update the
same rows from within long-running transactions (since courseware
is relatively slow).

The risk with this is that since the whole view execution is no
longer wrapped in a big implicit transaction, it's possible that
XBlock state will update and things that key off of that (e.g.
completion progress information or pre-req milestones) will fail
in a way that will leave the database in an unplanned-for state,
though this is already the case for those actions that trigger
asynchronous tasks like grades recalculation.

The query counts for the index view test were adjusted down
because save points count towards the total and we're no longer
setting them at the top level around the view as a whole.

Django2 bulk_email: bytestring conversion

Django2 enrollments app: course_id string

Django2 Badges: fix course_id string

* Converting variable to string before assignment in tests

Django 2 is stricter of string typing, so it will no longer do implicit conversions in some cases.
While the release notes only mention dropping bytestring support in some places, they seem to have also dropped implicit conversion to str for whole host of things.

Django2: Add to tox.ini's envlist

Upgrade edx-when