transparent app drawer background

50% transparent app drawer background

fact: the default "all black" app drawer background is horrible and many user uses another launcher only to change the app drawer background...

solution: transparency should be configurable, but I think this is a good starting point.
 
![Screenshot](https://f.cloud.github.com/assets/1644091/97190/a6ddbca8-66e4-11e2-8de7-6d33efbaab1f.png)