Added 2 new booru sites to sites.json

[CaramelFur]

I added furry.booru.org and realbooru.com
plz merge

[AtoraSuunva]

api is no longer a single url, but now an object for future support of more booru functions (like the new Post.postView getter)

paginate is also needed since by default it uses page, although page= already used in the url (So we need to specify pid instead)