Minor fix, fixes #959

[smoleniuch]

It fixes sql queries for listing orders in admins panel.

This query was being made before fix:

select `ti_orders`.*,
 concat(first_name, ' ', last_name) as `full_name`,
 (select status_name from `ti_statuses` where `ti_orders`.`status_id` = `ti_statuses`.`status_id`) as `status_name`,
 (select name from `ti_payments` where `ti_orders`.`payment` = `ti_payments`.`code`) as `payment` from `ti_orders`
 order by `location_name` asc 

After fix

select `ti_orders`.*,
 (select location_name from `ti_locations` where `ti_orders`.`location_id` = `ti_locations`.`location_id`) as `location_name`,
 concat(first_name, ' ', last_name) as `full_name`,
 (select status_name from `ti_statuses` where `ti_orders`.`status_id` = `ti_statuses`.`status_id`) as `status_name`,
 (select name from `ti_payments` where `ti_orders`.`payment` = `ti_payments`.`code`) as `payment`
 from `ti_orders` order by `location_name` asc

Based on my poor MySQL knowledge, location_name column does not exists in orders table.
It should be parsed through relation with locations table.

Query is generated somewhere here
But i cant figure it out where exactly.