Fix delete messages in course outline
STUD-2019
Merge pull request #4601 from edx/benmcmorran/delete-message

Fix delete messages in course outline
Display "IS VISIBLE TO" when released and published
Reword staff lock prompt and notifications
Change "View Published Version" to "View Live Version"
Change "Unit Tree Location" to "Unit Location in Course"
Switch live content warning based on unpublished changes
Reword discard changes confirmation prompt
Reword unit location tip
Add "Edit the name" popup text for sections and subsections
Fix popup text for section and subsection titles