Remaining UI papercuts for 2.0

[rdbende]

• More spacing between book subtitle and progress bar. (Redesign book detail view #948)
• Not sure, if book progress should be a bar. It's confusing, since we already show a progress bar in the player bar, but for different purpose. (Redesign book detail view #948)
• A status label missing for when the timer is actually running. (Add back system power control for sleep timer #981)