Added Pagination to relevant functions

* Added some helper functions in utils
* Called helper functions from:
    + followers
    + following
    + orgs
    + issues
    + collaborators
    + repos
    + watchers
    + watched
    + forks
    + starred
    + stargazers
* Called all those functions to make sure they still work. Having unit tests would be helpful.

The helper functions take care of making all the `get` calls. It re-uses the headers to make sure that authenticated requests are all authenticated. `stargazers` handles a `per_page` argument; all of the functions handle a `result_limit` argument.

By default, all results are returned. If `result_limit` is set, then pages are read until either we run out of pages or we think we've reached/exceeded the result limit. Since the default page size is 30, this means that `result_limit=20` will produce 30 results, and `result_limit=100` will produce 120 (if there are that many).