improve "no search results" message for barcode search

[danmichaelo]

The message shown when no search results are returned from a barcode search was never very precise, and this change made it even worse by blanking the search term :)

No search results found for "", check your spelling or try a less specific search

Since there is certainly no need to blame the user for spelling mistakes in the case of barcode lookup, we could adjust the message to something like

This book was not found in the Science Library. The nice librarians working there might still be able to order it to you from another library.

or something along those lines :)