Bug 29030: Make authorized value and description fields required

Bug 29030: Make authorized value and description fields required

This patch modifies the markup of the "Create a new authorized value"
modal so that a minimum set of fields is required: Authorized value and
description.

The patch also modifies the JavaScript which handles the submission so
that the jQuery Validation plugin can handle the field checks.

The spelling "authorised" is changed to "authorized" following coding
guidelines.

To test, apply the patch and rebuild the staff interface CSS
(https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_client).

- Locate a record in the catalog which has items and open an item for
  editing.
- In the add item form, test the process of adding an authorized
  value on the fly with the following fields: Withdrawn, Lost,
  Damaged, Use restrictions, Not for loan, Collection code, Shelving
  location, and Shelving control number.
  - In each case you should be able to type a new value in the
    dropdown's search box and be shown the option "Select to create."
  - Selecting should trigger a modal window, "Create a new authorized
    value."
  - Test that both "Authorized value" and "Description" fields are
    required, and the form can't be submitted without them.
  - Test that an error message shows up when you submit an authorized
    value which already exists, e.g. authval "1" for "DAMAGED."
  - After triggering this error, click the "Cancel" button and try
    creating another new authorized value. When the modal reopens the
    form should be reset: No previously-entered data, no error messages.
  - Submitting a valid form with a new authorized value should work
    correctly. The modal window should close automatically.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>