In DE-1822, we believed we needed to switch to start_date and end_date.
It was determined this was not the case, so this updates the comment
to ensure future users use the correct fields (start and end) and
updates any pieces of code that may have used start_date or end_date.
* Generate common/djangoapps import shims for LMS
* Generate common/djangoapps import shims for Studio
* Stop appending project root to sys.path
* Stop appending common/djangoapps to sys.path
* Import from common.djangoapps.course_action_state instead of course_action_state
* Import from common.djangoapps.course_modes instead of course_modes
* Import from common.djangoapps.database_fixups instead of database_fixups
* Import from common.djangoapps.edxmako instead of edxmako
* Import from common.djangoapps.entitlements instead of entitlements
* Import from common.djangoapps.pipline_mako instead of pipeline_mako
* Import from common.djangoapps.static_replace instead of static_replace
* Import from common.djangoapps.student instead of student
* Import from common.djangoapps.terrain instead of terrain
* Import from common.djangoapps.third_party_auth instead of third_party_auth
* Import from common.djangoapps.track instead of track
* Import from common.djangoapps.util instead of util
* Import from common.djangoapps.xblock_django instead of xblock_django
* Add empty common/djangoapps/__init__.py to fix pytest collection
* Fix pylint formatting violations
* Exclude import_shims/ directory tree from linting
