Bug 31040: jsTree image being used outside of jsTree plugin

Bug 31040: jsTree image being used outside of jsTree plugin

This patch corrects OPAC templates which tried to use a jsTree image
asset which is missing following the jsTree upgrade (see Bug 11873).
Templates should use /images/spinner-small.gif instead.

To test, apply the patch and enable OpenLibrarySearch and populate
OverDrive and RecordedBooks preferences with credentials (they don't
have to be valid).

Perform a catalog search in the OPAC. When the search results page first
loads you should see messages about the services being queried:

Searching OpenLibrary...
Searching RecordedBoks...
Searching OverDrive...

Each should show a working "spinner" image while the queries are being
performed. If you have valid OverDrive credentials you can try clicking
through to the OverDrive search results page to confirm that the image
is working on that page too.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>