Dark Theme: issue #454.

https://github.com/mozilla/MozStumbler/issues/454

I needed a change from the white screens, so I took a crack at this.

Checked on android 4.4.3 and on a 2.3.3 emulator:
https://www.dropbox.com/s/yrtpo6ul6itg14g/Screenshot%202014-06-23%2019.16.37.png