fix issue 1713090: After a Bluetooth call, MusicPlayer starts playing on...

fix issue 1713090: After a Bluetooth call, MusicPlayer starts playing on speaker rather than wired external audio.

Temporary fix until audio routing is refactored in Eclair release:
- centralized and synchronized all audio routing control in AudioService.setRouting()
- deprecated AudioManager.setRouting() and AudioManager.getRouting() methods