Issue response should return CommentsUrl

[shiftkey]

https://developer.github.com/v3/issues/#list-issues

{
    "id": 1,
    "url": "https://api.github.com/repos/octocat/Hello-World/issues/1347",
    "labels_url": "https://api.github.com/repos/octocat/Hello-World/issues/1347/labels{/name}",
    "comments_url": "https://api.github.com/repos/octocat/Hello-World/issues/1347/comments",
    "events_url": "https://api.github.com/repos/octocat/Hello-World/issues/1347/events",
    "html_url": "https://github.com/octocat/Hello-World/issues/1347",
    "number": 1347,
    "state": "open",
    ...
}

See #882 for related discussion.

[naveensrinivasan]

Can I take this one?

[haacked]

@naveensrinivasan go for it!

[haacked]

I assigned myself so nobody takes it. But go ahead and work on it @naveensrinivasan

[M-Zuber]

This is awesome. Let's me throw out ~200 loc and tests!

[shiftkey]

Fixed in #884