Added Dashclcok extension

Added a Dashclock extension because I wanted it :D. The code could probably be optimized a bit but it works. Tested on Galaxy Nexus running Android 4.2.
![Screenshot_2013-04-12-14-51-20](https://f.cloud.github.com/assets/3937996/371597/c8cce10a-a33d-11e2-8138-48ef3630aaeb.png)