WIP: Add a Starred client

Because i like :stars: and they're my favorite way of discovering all the stuff that i wish i had thought of myself but don't have to.

Once i get over my pride, i realize how much psychic weight (:anchor:) has been lifted by leveraging so many smart peoples' work.

Sidenote: thanks for putting together a great library :smile:. i found adding this piece to the library to be :cake:.

Work left:

* [x] Add tests for stars for authenticated user and passed user
* [x] Accept sort parameters for the above
* [x] Implement stargazers
* [x] Check if user has a repo starred
* [x] Star/Unstar a repo
* [ ] Tests for everyone :fist: