setLocked shows white locked icon in track

![screen shot 2013-07-15 at 6 22 51 pm](https://f.cloud.github.com/assets/1039404/802086/4202c40a-edb6-11e2-9df8-5612967cd751.png)

setLocked shows white locked icon in track when switch is on. 

Still have to set switch to on and set user interaction to disabled separately.

Shadow and animation speeds closer to iOS 7 beta 3 look.