Add powerd normal mode flag (-n)

When the AC line state is unknown powerd looks to the -n flag. Added the ability to set this flag.
![screen shot 2014-10-05 at 6 49 11 pm](https://cloud.githubusercontent.com/assets/8129878/4520220/e0ca17ce-4ce1-11e4-86bf-ce058fe41cf9.png)