5034: Improve Workbench collection display.

5034: Improve Workbench collection display.

* Display the UUID, and make it auto-select for easy copying.
* Do the same for the portable data hash, and call it the content
  address to emphasize that.
* Display information about the collection's size on the show page and
  preview pane.  This relies on an updated Ruby SDK.
* Clean up code that checks for a portable data hash in the UUID.
  That can't happen anymore thanks to the redirect/list display logic
  in the controller.