Add tests

Also let xml import work on modulestores that don't use write signaling

STUD-724

Test course for allowing custom formatting of due date strings.

STUD-724

Try making the name of the course match the folder name.

More cleanup.

More cleanup.

updates.

Fixed test_masquerade failure due to not clearing the modulestore
between 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

Moved xml_store_config, mongo_store_config, and draft_mongo_store_config to xmodule/modulestore/tests/django_util.py
Removed some repeated instances of xml_store_config.
Reverted some changes to mongo_store_config so each modulestore gets it's own uuid.

In the middle of addressing pull request comments. This is a safety commit in case I have to revert some changes I'm about to make.