LP1898775: Add basket to bucket in bootstrap

LP1898775: Add basket to bucket in bootstrap

The bootstrap OPAC uses links, rather than <select> for the basket dropdown, so the
existing event listener couldn't get attached to the correct element.

To test:
1. Confirm that you are using the bootstrap OPAC.
2. In the staff client, select the traditional staff catalog.
3. Add several items to your basket.
4. Click the basket icon, and select 'Add Basket to Bucket'
5. Note that you get a 404 error.
6. Apply this patch.
7. Repeat steps 1-3.
8. Note that you can now select a bucket, and that the process completes successfully.

Signed-off-by: Jane Sandberg <sandbergja@gmail.com>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>