Add delete pet functionality to the admin user #433

[Popokok]

@josdem I added the button and used same modal as in pet/list.html. I also made some changes so the design looks the same as in user pet list. If there is anything that is not to your liking, just let me know and I'll fix it right up.

[josdem]

@all-contributors please add @Popokok for code

[allcontributors[bot]]

@josdem

I've put up a pull request to add @Popokok! :tada: