This centralizes the logic for group membership, and means that we
don't need to make queries to find out whether the legacy groups names exist.

LMS-1355

LMS-1307

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

add fixes for 500 bugs (lighthouse 287 and 293) by requiring login for accessing licenses and inline discussions.  Add unit tests for licenses, and rearrange tests based off of (the former) PageLoad.  Also cleanups for pylint and pep8.

append some character, in this case a '_', if the course number is really a full-on number. The Wiki library interprets this incorrectly - to date we've always used non-numerical values.

Wiki pages can now be viewed from the course URL and the course nav is shown. It doesn't follow the user yet.