D expand

Changes
------------
- mini refactor of comments.js (moving away from `Component` magic™)
- added expand/collapse thread button

![image](https://cloud.githubusercontent.com/assets/960919/4558115/a326c3f8-4edb-11e4-819e-d1fba42c6661.png)

![image](http://im.ezgif.com/tmp/gif_rev_1412766402_bbc23274a6.gif)
hard to read this. split the chaining, so `hasClass` is on its own

```
var $target = bonzo(e.currentTarget).toggleClass(offClass),
      expand = !$target.hasClass(offClass);
```