Add edit info to instantiated xblock in update_item
Refactor to use usage_key_with_run in item.py
Merge pull request #4544 from edx/benmcmorran/fixes-from-bulk-publishing

Return edit info from update_item and refactor item.py to use usage_key_with_run
BLD-1104: List units that use group configuration.
REVERT THIS COMMIT BEFORE MERGE.
Addressed comments.
Added Anton's fixes from other branch.
Fixed 1 problem in bok-choy tests.