Bug 15196: Default sorting of patron lists

 Bug 15196: Default sorting of patron lists

This patch sorts users by surname.
Also string fix -> Firstname to First name in column heading

To test:
1) Go to a patron list
2) Confirm it is sorted by surname
3) Add a patron that will need to slot in the middle somewhere
4) Confirm the data table sorts it correctly
5) Confirm column heading change

Sponsored-by: Catalyst IT
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>