Embeds and minor bugfix

![screenshot from 2014-08-06 11 52 34](https://cloud.githubusercontent.com/assets/338853/3832141/e679c212-1d9a-11e4-89d1-978418778a56.png)

Some improvements to the in-subreddit embed based on various feedback including https://www.reddit.com/r/spacex/comments/2cce9t/rspacex_asiasat_8_official_launch_discussion/cjhnun6

In short, this makes the embed look more natural in a subreddit as it's a) made to look more like a self-post by default and b) influenced by the embedding subreddit's stylesheet.

A couple of caveats: 
* for security purposes and expediency, styling does not work for private subreddits at the moment.
* the static description text is still not shown in any way in the embed. this needs to change.

Also contains a bonus bugfix for https://www.reddit.com/r/live/comments/2c3mmr/bug_description_provided_when_creating_live/

:eyeglasses: @umbrae @Deimos 
Nit: feels a tiny bit strange to use `style_sr` internally but `stylesr` as the query param.