LP#1584807: Clicking column header should not unsort list

LP#1584807: Clicking column header should not unsort list

Clicking column headers in My Account cycled through ascending order,
descending order, and then unsorted. But unsorting a list after clicking a
header is unintutive to the user. Instead, it should toggle between ascending /
descending order.

Test plan
* Using the concerto dataset, log in as user 99999395984 / maes1234
* Go to the Items Out area of my account and click the title column header to
sort the list.
* The list will first sort alphabetically in ascending order, on a second click
will sort alphabetically in descending order, and, on a third click, will
return to the default sort order.
* After loading the patch, clicking the column header should only result in
sorting in ascending and descending order.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Jason Stephenson <jason@sigio.com>