some alignment fixes for the new username position

* username, date, and gutter share baseline 
* fixed date/reply-to-tab overlap on narrow browsers

:microscope: 

![screenshot 2014-04-30 10 23 20](https://cloud.githubusercontent.com/assets/1681963/2842314/0335ea36-d073-11e3-99e0-4ee1452ddee1.png)