Fixing broken layout when username is too long.

Adding max-width attribute to username field. Showing ellipsis when text
overflows
Adding media queries to provide a better layout when browsing on tablets
or mobile.
Fixes Bug 1038920
I think the top organizer section can stay centered though.

![screenshot 2014-08-06 12 00 28](https://cloud.githubusercontent.com/assets/206379/3832261/25addb20-1d9c-11e4-8ed2-84732ff01090.png)