Xposed module for expanded volume panel
The feature you have requested (Expandable Volume Control) is present in GravityBox (Lollipop). 

You can find it at the Xposed Repository . 

You can download it directly here (3.54 MB). 

However, do note that the Xposed Framework is still in Alpha, so some features of the module might not work properly. If you find any, do report them at the official XDA thread for this module. Any discussions can be done there too.