Removed the ugly dotted border on controls in carousel for firefox

I guess the firefox users enjoy the dotted border on focus but it looks very ugly in the carousel, so I think it's better off without it..

![screen shot 2013-09-18 at 1 39 54 pm](https://f.cloud.github.com/assets/125676/1164484/9f6301d0-2058-11e3-877e-d04ba5af792d.png)