Bug 32027: Fix 'librarian interface' to use 'staff interface' in Pages/HTML customiza...

Bug 32027: Fix 'librarian interface' to use 'staff interface' in Pages/HTML customizations/News

This changes all occurences of "librarian interface" to the
correct term "staff interface"

To test:
* Create a new Page
* Verify that the pull down for location has "librarian interface"
* Save your page
* Verify that the list of existing pages has "Librarian interface" as
  label for the link
* Verify that when you hover over on those links the titles read
  "librarian interface" as well
* Apply patch
* All those should read correctly now.

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>