Support pagination

[durnin]

Some results for github's API are returned paginated (i.e. when more than 30 results in a public repo: https://developer.github.com/v3/guides/traversing-with-pagination/#basics-of-pagination). The pagination links are returned in a header like this:

Status: 200 OK
Link: <https://api.github.com/resource?page=2>; rel="next",
      <https://api.github.com/resource?page=5>; rel="last"

A nice to have would be that this is completely transparent and all results are returned. An easier solution would be to give access to this Link headers to the user so that he can send the requests himself.

[Update] This is an improvement to # #24