Bug 37187: Fix deletion of label batches and label templates

Bug 37187: Fix deletion of label batches and label templates

This patch uses the new form-submit JS to convert the label management
deletion link from a GET operation to POST.

To test, apply the patch and go to Cataloging -> Label creator.

- Click Manage -> Label batches. Create a batch if necessary.
- Click the "Delete" button in the "Actions" column. You should get a
  confirmation message, "Are you sure you want to delete this?"
  - Test both the confirming and cancelling.
- Perform the same test with Manage -> Label templates.
- From the Manage -> Label batches page, click "edit" on one of the
  batches.
- Right above the "Items in batch number X" is a toolbar which should
  have a button, "Delete batch." Test that it works correctly to delete
  the batch.

Sponsored-by: Athens County Public Libraries
Signed-off-by: Phil Ringnalda <phil@chetcolibrary.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>