Discussion goto featured comment

We can now be taken to the comment in context of the conversation.
This has been done (almost) silently until the new design comes out, which might have a more clear CTA (it's on the created date).

There was also some bug fixes:
* `/discussion/comment-redirect/` should definitely be `/discussion-permalink/`
* Load newer comments link didn't appear if it wasn't there from the last render

![Down down down](http://www.netanimations.net/lined-ball-rolling-animation.gif)