Bug 15983: Use Font Awesome icons in serial numbering pattern deletion confirmation...

Bug 15983: Use Font Awesome icons in serial numbering pattern deletion confirmation dialog

If you try to delete a serial numbering pattern which is in use by an
existing subscription you will be shown a confirmation dialog. This
dialog should use Font Awesome icons.

Other minor changes:

- Added "action" attributes to <form>s to fix validation errors.
- Added "alert" class to confirmation dialogs so that they correctly
  styled.

To test, apply the patch and go to Serials -> Numbering patterns.

- Click "Delete" on a numbering pattern which is in use by a
  subscription.
- Verify that the confirmation dialog is styled correctly.
- Test that the "No, do not delete" button works correctly.
- Test that the "Yes, delete" button deletes the correct numbering
  pattern.

Signed-off-by: Hector Castro <hector.hecaxmmx@gmail.com>
Works as described

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com