TNL-2321

- added entrance exam check on course info
- staff can by pass gating and added tests
- refined gating logic
- changes after rebasing with Asad's branch
- check ENTRANCE_EXAMS feature is enabled
- updated test to reflect new logic
- catering anonymous user in entrance exam permission
- fixed broken tests
- change after feedback on 16/3
- fix for a broken test
- created new entrance_exams module
- fixed quality error and improved test coverage
- put get_required_content back in milestones helper
- Refactored entrance exams logic
- Refactored tabs logic
- Fixed broken unit test
- changes after feedback from dan-f on 3/27
- removed unnecessary user.is_anonymous check
- Addressed PR feedback
- Addressed commit-specific feedback
- Rework guard clauses
- Add coverage for course info case

Conflicts:
	lms/djangoapps/courseware/courses.py
	lms/djangoapps/instructor_task/api.py

refined entrance exam student attempts reset

Quality improvements 1/16

added rescore, delete state and task history functionality

added unit tests for entrance exam reset attempts

added unit tests for re scoring of entrance exam and task history

improved test coverage

Got rid of pep violation

feedback changes and added jasmine test

added more jasmine tests for Javascript changes

added bok-choy tests for UI changes

replaced input containing <p> tags with <label>

Removed ee element assertions to avoid js error

Added call to super.setUp()

changes based on feedback on 2/18

Writing tests in JS instead of coffee script

commit related to skip entrance exam 2/13

fixed bad-continuation quality error

fixed broken bok-choy test

changes based on feedback on 2/18

added js tests and removed coffee script tests

fixed broken bok-choy and unit tests

changes left while rebasing

rephrase test titles

do not need these libs

changes based on feedback on 2/24

changes text which was left

Changes based on feedback on 3/3

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]

TNL-1304

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

PLAT-88

add tests for static tabs

LMS-11189

[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]

Changed "Status Page" -> "Page".

UX:
    support for displaying built-in tabs
    restored drag and drop on Studio Pages
    additional styling for fixed state on Studio Pages
    add a new page action added to bottom of Studio Pages

Dev
    changes for viewing tabs in studio,
    refactored the tab code,
    decoupled the code from django layer.
    is_hideable flag on tabs
    get_discussion method is needed to continue to support
external_discussion links for now since used by 6.00x course.
    override the __eq__ operator to support comparing with
dict-type tabs.

Test
    moved test code to common,
    added acceptance test for built-in pages
    added additional unit tests for tabs.
    changed test_split_modulestore test to support serializing objects
that are fields in a Course.

Env:
    updated environment configuration settings so they are
    consistent for both cms and lms.

LMS-1192

Add tests

Modified navigation tests to use MixedModulestore
Updated factories to find editable modulestore

Updated test_submitting_problems

Updated test_tabs.py

Updated test_view_authentication

Updated test_views

Updated courseware/tests/tests.py

Updated test_masquerade

Updated test_module_render

Pylint fixes

Updated video and word cloud tests

Updated course wiki tests

Updated license and open_ended tests.
One open_ended test still failing due to Mako initialization issues

Updated staticbook

Updated django_comment_client tests

Updated instructor tests

Updated instructor task tests

Updated external_auth tests

Updated course_groups

The help tab opens a modal dialog that directs the user at various resources
(e.g. the site FAQ and course forums) and allows the user to submit feedback
to the feedback endpoint (which will ultimately create a ticket for the
student support team).