Fix merge problem
fixed discussion preview back to the way it was
Fixes view and preview buttons on unit page
Mark UnitPublishingTest as a test.
Merge pull request #4434 from edx/frances/discussion-preview-fix

fixed discussion preview back to the way it was
Merge pull request #4436 from edx/benmcmorran/fix-view-buttons

Fixes view and preview buttons on unit page
Updates based on merge with master.
First pass at locking.
First bok choy test for visible_to_staff_only.
First cut at staff lock UI
Show the correct block color for all states
Fix merge issue.
Implement first set of staff only tests
Fix publishing unit tests
BDD text.
Fix remove lock test to confirm first
Bok choy tests for staff locking from Studio unit page.
Small BDD wording change.
Address code review comments