setLocked shows white locked icon in track

![screen shot 2013-07-15 at 4 09 16 pm](https://f.cloud.github.com/assets/1039404/801543/99a1c516-eda3-11e2-90d3-d4a51cafecd2.png)

setLocked shows white locked icon in track. Still have to set switch to
on and set user interaction to disabled separately.

Shadow closer to iOS 7 beta 3 look.

Animation speeds closer to iOS 7 beta 3, though not quite exact.