Track Akismet spam checks, reflect on comment addition log #472

Fixes #472 by properly detecting Akismet response on new comments, and reflecting on new comment log `comment_type` added in #558. So users now should be able to filter auto-spammed comment easily.

@fjarrett @lukecarbis Please review/test.

/cc @krogsgard Can you [checkout this branch](https://github.com/x-team/wp-stream/archive/issue-472.zip) and confirm this solves your issue on #472 ?
@shadyvb I think we should also add some Steam meta here to indicate in the summary that Akismet had involvement with the action.

![screen_shot_2014-06-30_at_1_03_20_pm](https://cloud.githubusercontent.com/assets/522158/3433604/1f3fc204-0081-11e4-8e11-e4f2e6e6b8ab.png)