Improve Ease of administration of Pets by adding sorts and increasing pager.

I have about ~70 pets emails which get fired out from my website.

I'm about to clone all of them and start "A/B" testing by randomly picking the original or slightly modified clone.

PETs has always been hard to manage due to the multiple pages and default unchangeable sort.

I've resolved this by increasing the listing from 25 to 100. And also made it so the table columns are sortable. Previously it was sorting by "entity_id", but now you can sort via machine_name or status. So if you pick good machine names, then it should be easy to organize your pets.