simplejson has been removed from future versions of Django (which we will eventually use).

TNL-650

I can't seem to find any references to this code outside of the library
and the tests themselves.

The existing pattern of using `override_settings(MODULESTORE=...)` prevented
us from having more than one layer of subclassing in modulestore tests.

In a structure like:

    @override_settings(MODULESTORE=store_a)
    class BaseTestCase(ModuleStoreTestCase):
        def setUp(self):
            # use store

    @override_settings(MODULESTORE=store_b)
    class ChildTestCase(BaseTestCase):
        def setUp(self):
            # use store

In this case, the store actions performed in `BaseTestCase` on behalf of
`ChildTestCase` would still use `store_a`, even though the `ChildTestCase`
had specified to use `store_b`. This is because the `override_settings`
decorator would be the innermost wrapper around the `BaseTestCase.setUp` method,
no matter what `ChildTestCase` does.

To remedy this, we move the call to `override_settings` into the
`ModuleStoreTestCase.setUp` method, and use a cleanup to remove the override.
Subclasses can just defined the `MODULESTORE` class attribute to specify which
modulestore to use _for the entire `setUp` chain_.

[PLAT-419]

JIRA: PLAT-348

TNL-735

TNL-670

JIRA: TNL-710

IMPORTANT: this commit converts the course_groups
package to using migrations.  When deploying to an
existing openedx instance, migration 0001 may fail
with an error indicating that the CourseUserGroup
table already exists.  If this happens, running
the 0001 migration first, with the --fake option,
is recommended.  After performing this step,
remaining migrations should work as expected.

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

should be 'if cond is None:'

TE-489

Depends on cs_comments_serivce commit ea218a2b038b59e63fd6593b5598db90223636e1.

TNL-543

Co-Authored-By: Brian Talbot <btalbot@edx.org>

TNL-549

If we use unicode character in the search of forum
it will cuase the error which is not the desired
behavior it should check and return result.

TNL-336

TNL-552

TNL-172: Change type of a previously posted post. IMPORTANT: this commit depends on commit 774887b in cs_comments_service.

When the new post is created under the subcategory and it appear
after the creation, it doesn't have the link of category/subcategory
after thread body. When we reload the page the link appears. Link
should appear after creation.

TNL-404

TNL-444

TNL-24

TNL-186