add feature flag ui to admin menu


![image](https://f.cloud.github.com/assets/249606/2138111/4fb1eaa2-9330-11e3-8025-43873b4e0c30.png)

![image](https://f.cloud.github.com/assets/249606/2138107/42656aea-9330-11e3-9856-0643bf5da990.png)