add per_page results to filters

[Blesta Addons]

in so many places, we need a custom quantity result, there are no way to change this from admin interface or make it custom for clients, we need to change this value from config file and it apply to all Blesta system, per default is 20 results.

it would be nice if we can select how many result we want from the filter options.

[Blesta Addons]

        // Set Per Page result
        if (!empty($filters['per_page'])) {
            $this->setPerPage($filters['per_page']);
        }