strip ANSI color sequences from ls output in the #status-dir-cwd panel

This occurs when the env has `CLICOLOR=1` and `TERM=xterm-256color` (possibly other slightly different configurations as well)

Before
![screenshot 2014-01-08 20 49 22](https://f.cloud.github.com/assets/26596/1875149/77cb3874-78e9-11e3-9414-c956110f8224.png)

After
![screenshot 2014-01-08 20 48 10](https://f.cloud.github.com/assets/26596/1875151/7a0cfaa0-78e9-11e3-93ea-dbd6307ca865.png)