Highlight comments from the post author

Fixes #1360

I did create small badge to highlight the post author in comments displayed by Reader. Don't know what is the process for localisation so I just made the NSLocalized string for the badge name.

![ios simulator screen shot 23 jul 2014 11 24 21](https://cloud.githubusercontent.com/assets/151760/3671175/d868224e-124c-11e4-919f-2a3f06bcc4e4.png)