Bug 15920: Clean up and fix errors in batch checkout template

Bug 15920: Clean up and fix errors in batch checkout template

The batch checkout template has some markup and JavaScript problems
which need to be resolved, including:

- Mismatched <h3></h1>
- JavaScript includes which are not used
- Incorrect DataTables configuration
- Incorrect class on warning dialogs
- Incorrect terminology: Use "checkout" instead of "issue"

This patch also changes the markup and styling of batch checkout errors,
using Font Awesome icons to retain highlighting of warnings and errors
while (I hope) improving readability.

To test, apply the patch and go to batch checkout for a patron for whom
batch checkouts are enabled.

- Check out a batch of barcodes. Include items which will trigger errors
  or warnings. For example: Invalid barcodes, lost items, items which
  are already checked out, items which are on hold for another patron,
  items which are damaged.

- When the table of items is displayed so that you can confirm the
  checkout, make sure the table is sortable.

- Think about whether the style changes on warnings and errors are an
  improvement.

- Try to initiate a batch checkout to a patron who is restricted. You
  should see an "alert" style dialog instead of a "message" style one.

- Validate the HTML and confirm that there are no errors raised by this
  template's markup.

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