set status bar icon color to NULL for Launcher

(removes blue tint from status icons on homescreen when using the
default PA Colors)
From this:
![screenshot_2013-08-26-15-00-19](https://f.cloud.github.com/assets/2973420/1028723/bcc1b818-0e8b-11e3-8006-e8237e12a2b5.png)
To this:
![screenshot_2013-08-26-15-01-26](https://f.cloud.github.com/assets/2973420/1028724/c3a31f1e-0e8b-11e3-920f-3522a60e79ff.png)