Cleanup UI properly after error

I observed that after a failure, the UI did not clean itself up
properly. Subsequent exports worked, but would continue to display the
earlier failure message.

I reworked the displayManager to be a little simpler as well.
Merge pull request #1621 from steventlamb/bug/export_ui_cleanup

Cleanup UI properly after error
Don't hard code instance names in tests
Mask details about comment when moderator hides
Merge pull request #1623 from steventlamb/topic/hidden_comment_ui

Mask details about comment when moderator hides
Show Flagged By and Previously Flagged By on comment moderation
Unlocalize comment ids