Non-push comments, step 1

There's no reason not to include the new comment's ID in the response.
Non-push comments, step 2

Once we have the comment ID in the AJAX response, we can just skip push.
Non-push comments, step 3

Also add dupe protection in the AJAX callback for the comment fetch.
Merge pull request #85 from ayust/patch-1

Non-push-reliant commenting