Revert "Merge pull request #3889 from edx/diana/fix-gen-cert"

This reverts commit 779480ba39287ff689f9965fe4322b9b9e31bbde, reversing
changes made to 797a1643ec0673b7b79973cefc75bc2edeb15d1d.
Revert "Merge pull request #3869 from edx/dhm/bug_get_children"

This reverts commit 9d2db736df29f2aa1697e0511d352243d83d209e, reversing
changes made to 0a909a9b24472f3acff041b4935c9c069344e1be.
Revert "Merge pull request #3861 from edx/sarina/fix-quality"

This reverts commit d01af063a63374f688e01d7b77ae5e652284093f, reversing
changes made to b56e12ff032a6319eefb66d7366e7b461836b9bb.

Conflicts:
	lms/djangoapps/instructor/tests/test_spoc_gradebook.py
Revert "Merge pull request #2905 from edx/opaque-keys"

This reverts commit ecb05e6b031dd525a3752a7c5fd70755e27ece59, reversing
changes made to c96bf07be6dff4e5b8f3992b8c690abe2876f1b3.

Conflicts:
	cms/djangoapps/contentstore/views/component.py
	cms/djangoapps/contentstore/views/item.py
	cms/djangoapps/contentstore/views/tests/test_item.py
	cms/static/js/views/modals/edit_xblock.js
	cms/templates/container_xblock_component.html
	cms/templates/studio_container_wrapper.html
	cms/templates/studio_xblock_wrapper.html
	cms/templates/widgets/sequence-edit.html
	common/djangoapps/static_replace/test/test_static_replace.py
	common/djangoapps/student/models.py
	common/lib/capa/capa/tests/test_inputtypes.py
	common/lib/xmodule/xmodule/split_test_module.py
	common/lib/xmodule/xmodule/studio_editable.py
	common/lib/xmodule/xmodule/x_module.py
	lms/djangoapps/bulk_email/tasks.py
	lms/djangoapps/courseware/access.py
	lms/djangoapps/courseware/module_render.py
	lms/djangoapps/courseware/tests/test_access.py
	lms/djangoapps/courseware/tests/test_view_authentication.py
	lms/djangoapps/courseware/views.py
	lms/djangoapps/instructor/enrollment.py
	lms/djangoapps/instructor/tests/test_api.py
	lms/djangoapps/instructor/tests/test_legacy_enrollment.py
	lms/djangoapps/instructor/tests/test_spoc_gradebook.py
	lms/djangoapps/instructor/views/api.py
	lms/djangoapps/instructor/views/instructor_dashboard.py
	lms/djangoapps/instructor/views/legacy.py
	lms/djangoapps/shoppingcart/tests/test_views.py
	lms/static/js/staff_debug_actions.js
	lms/templates/courseware/instructor_dashboard.html
	lms/templates/staff_problem_info.html