Bug 16938: Remove the use of "onclick" from batch patrons modification template

Bug 16938: Remove the use of "onclick" from batch patrons modification template

This patch revises the batch patrons modification template, removing
"onclick" attributes from the markup and defining those events in the
script.

To test you should have at least one extended patron attribute
configured.

- Apply the patch and go to Tools -> Batch patron modification.
- Submit a batch of patrons for modification.
- Confirm that the checkbox next to any required field is disabled.
- Select a date in the registration date and expiry date fields. Confirm
  that the "Clear" link next to each empties the correct field.
- Click "New" next to a patron attibute. A copy of the patron attribute
  line should be created.
- Click "Delete" next to a cloned patron attribute. The correct line
  should be removed.

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

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>